At the present time, no custom code can run locally. That includes Rboy’s DTHs and smartapps.
However, as @lflorack mentioned, the custom DTH is can be used to set the codes in the lock’s own memory at a time in the smartthings cloud was available, and then those codes would continue to be available even if you remove the smartthings hub all together.
And that holds true for ANY smartapp that has sent the codes to the lock. If the code is in the lock at the time of outage, it will continue to be in the lock for the duration of the outage. But to me, the app is pointless if all you’re doing is inputting the same static codes that you would input into the lock itself…
For the codes that need to work 24/7/365, such as my wife and myself and other household members, there is absolutely no value in storing the code in the app. In fact, that makes it less secure as the possibility of someone who gains access to the app but should not have such access now knows ALL your codes. (sorry about the run-on sentence)
The whole point of such an app IMO is to be able to grant/revoke access based on schedules.
So if the pool boy is supposed to get access from 4-8pm every Friday but the ST cloud is down from 3:00pm to 6:00pm on Friday, there’s no way the rboy app is getting that code to the lock.
Not impuning rboy or his apps at all. Word is it’s a great app.
I just don’t want us erroneously assigning capabilities that don’t exist to these apps.
You are correct. The “timed” events wouldn’t work. But that wasn’t my point. My point is you are having to manage each entry with manual codes. With RBoy app you can manage centrally any door in your ST. If power goes out those codes with 24X7X365 are still on those doors enabling access without ST.
As for whether it is secure or not I would have to call BS on that. Frankly my kids have no issues in telling anyone the codes to the house. Having a 24X7X365 code for them is more of a risk than having specific times they are usually home to access the home. Just my $0.02.
My viewpoint is different. Your 2nd category, Support for Complexity, seems to be a source of failure. I have had the system for 4+ years. I have no complexity and experience zero failures. I think my system has been reliable because I have refrained from cobbling multiple manufacturers together and from “creative programming.”
I am not advocating that others should also refrain, but I do feel my reliability is a direct function of my system’s simplicity. My devices provide a complete security system but, like others. relies on the internet itself. I have ST, Honeywell, and UtiliTech devices. I have Arlo but do not link it to ST. I use Google Assistant and use their room assignments instead of room assignments in ST or Samsung connect.
I was pleased that Samsung bought the company. Since that purchase the hardware and software designers have been converging, which is the Apple strategy to be both.
This has been my experience. I live is So.Cal and my phone is Samsung. Thanks for letting me reply.
Hmm, no offense but that seems unlikely. Like when the entire platform is down. That’s happened quite a few times in the not quite 3 years I’ve had a ST hub.
I’m happy that your system has worked well for you, but it’s not just because you have gone for simplicity.
On multiple occasions over the last three years there have been problems with the stock DTHs for some of the most popular devices, such as the GE switches (at one point the DTH switched orientation, so that for a few days people had to press the top of the switch for off and the bottom for on – – this error was actually introduced twice in one year).
The platform outages which affected many customers rarely had anything to do with the customer’s own configuration, the cloud was simply not available.
It may be that you were not at home during the time of the outages, that you didn’t notice them, or even that you don’t remember them, a phenomenon that happens with quite a few people if the necessary workarounds are simple enough.
I myself have used almost no custom programming, and still have found multiple errors each year from the standard routines and features.
Again, not all of these problems will affect all customers, and sometimes they aren’t even noticed by some people.
So I’m glad your system has fully met your needs. I hope more people will be able to say the same in the future. 
That’s happen a lot in the last 3 months let alone 3 years. Another outage today too. Automations (even the Samsung only automations) are flaking out. Ugh ST is becoming a nussaince. I have a rPi3 with zwave board and soon zigbee usb dongle. I will be working on learning HA over the next few weeks to determine if I need to leave ST. I need lights to be reliable and more instantaneous. I need notifications to happen when the event happens (not 15-20 min later) to my phone either through apps or txts. Seems right when I am about to leave ST gets back to acceptable normal but then shortly after there is another partial or full outage. Such a shame that Samsung can’t keep this up and running even for a week. So promising too with all the great developer work going on here (askAlexa, Echssistant, Rooms, etc).
I tried having devices interact with each other, elaborate and simply automations. What interaction that does exist occurs at the Google Asst. level and not in the ST apps. My devices do not directly interact with each other outside of GA.
I subscribe to the status notifications so I am notified each time ST hiccups. My system works well. I first used Iris quite some time ago and it was down for over 6 weeks, which is why I switched to ST. The simplicity of my system cannot be overstated. It is my observation that much of the problems I read about result from an attempt to interconnect too much. It is clear that ST is not well designed for that so those needing that function should seek other solutions.
When I read about someone experiencing a falter, it rarely is about a failed device but most often a failure to execute a command to act upon another device. My devices do not do that and that is why I suspect my system is more reliable. There seems to be two layers to ST. One is the simple operation of a device and the other is the inter-coordination of devices as programmed/designed by a user. Except for the ST s/w update down-time, all my devices have worked faithfully.
My experience is not about being smug but I think it reasonable to include in this discussion that the complexities attempted by some users simply exceeds the design of the existing/evolving ST system. I do not see that as a ST failure. The appetite for complexity by users will only increase. It just seems that appetite is increasing at a rate ST cannot keep up with.
Thanks for the opportunity to respond. - Dan
I am heading over to Home Assistant (home-assistant.io). I have always complained about ST forcing firmware updates on you with short notice. And now cloud dependency is becoming a real issue for me.
With Home Assistant I was up and running within minutes basically and an hour later I had things integrated that were problematic on ST. My Foscam camera hooked right up and show a picture updated every 10 seconds and allows me to click into live video. This requires some work to get setup in ST and also requires a paid service for the developer of the ST DTH and SmartApp if you don’t want to program it yourself.
I also very easily connected my Ring Pro door bell including running last recordings. And my AppleTV an Osram Lightly gateway was setup within minutes. And presence with my internet router works perfectly, and I’ve been wanting to do this with ST to avoid the necessity for installing apps on all family devices. And although people here in the forums constantly say device monitoring via router is totally unreliable, I can’t confirm that. It works pretty good for me so far.
Unfortunately, Zigbee support on Home Assistant is not so great apparently (still waiting on my Zigbee USB stick to test), so I will be bridging over to ST via MQTT until I can migrate everything over.
But, my decision is made. Bye bye ST. It was good as a starter into the Smart Home world. But, I am willing to write in some text files for configuration to get the advantages of primarily local processing and a lot more device support than ST.
Have you looked at Hubitat?
All local processing and update or backup when you want 
That looks interesting. I will look into it. Thanks.
I have and while it looks great the majority of my lightswitches are Lutron Caseta and last I checked Hubitat only supports Lutron Pro … need to see if I can swap out my Caseta Bridge for a Pro Bridge without replacing all my switches again … meh –
Robin
I’m in the UK and have been playing for a while
Originally I had to disable z-wave to stay legal and change the psu, but with the latest update I’m using an aeon labs stick to provide z-wave
You can now buy a UK version with the correct frequencies and psu
Andy
Go on the Hubitat web page and when you click on buy you get an option for which hub you want.
I think they were a little surprised by the high level of interest from people in the UK. There aren’t any licensing issues because they use USB sticks from other manufacturers which are already licensed for the local region. It was just a matter of sourcing all the right components. 
Does it ??? hmmm… Thinking I will exit stage right shortly then 
Robin…
2am this morning they offered the update
You’ll notice I said offered… not forced
By 3am I had quite a few z-wave devices running
Andy
I don’t
However; if you have an ST driver for it you can probably convert it easily enough.