Of the options recommended here, I would strongly recommend against using Scout or Smartthings as your base for a home security system. I had Scout for 6 months and switched to SimpliSafe the beginning of last month due to the many issues with their system.
Scout Monitoring on Smartthings - besides the reasons already mentioned here, Smartthings doesn’t really have the reliability you should be after in a home security system. A Security system really needs to have 99.9999% uptime or better, and Smartthings is optimistically only topping out around 97% or so. Given that, and the lack of any cellular backup, you are honestly better off looking elsewhere. I like my Smartthings system alot, but I don’t trust it for home security.
Scout Monitoring with Scout hardware - Please don’t take my word for it, go check out their community forums yourself, their hardware is plagued with issues. I had this system for 6 months and ultimately pulled the plug because it didn’t have the reliability a reputable security system needs to have. Long story short, I had a false alarm the first day I was on vacation with my family out of the country. Not a fun thing to deal with when you have spotty cell phone coverage! It turned out it was due to a dead battery in the motion sensor. The crummy thing was, the monitoring company sent the local sheriff out to my house to check on things, all due to a dead battery that was just changed 2 months prior. Just in case you didn’t catch that, I changed a battery in the same sensor twice in 6 months. Oh, and by the way, there was no low battery notification either time. Add to that, their siren is nothing more than an obnoxious beep. The siren was acknowledged by Scout as a problem well over a year ago and they have yet to offer any realistic solution!
I’m using SimpliSafe now and so far so good, plus there are nowhere near the negative complaints about poor system performance (innovation may be another story…). From what I’ve been able to dig up, it may not be the slickest, most modern system out there, but it is reliable. If I’m not mistaken, this is also the only professional monitored alarm system that can be easily integrated to SmartThings without a good bit of effort - just install the device type and a smartapp and it works (Disclaimer: The API used by the SmartThings/SimpliSafe integration is not officially supported by SimpliSafe. This means it could break at any time with no warning whatsoever!). The other alarm options I’ve seen required a bit of effort to get working - some, however, have very good payoff once completed with an even tighter integration that what is currently available with SimpliSafe.
Abode, also looks very promising but is a larger investment up front and is still very new to the game. They do have a lot going for them, so it will definitely be a good one to watch!
Hopefully this is helpful to you, but as I mentioned, I would stay away from both of the Scout options for the time being. You can’t put a price on peace of mind!!!