Hi, the smartapp has been used for more than 3 years by many contributors, just look at the testimonials under the thread.
If you click on the post, there are some screenshots included in the post above, and there are more screenshots at the ST community wiki:
And, all the use cases supported are described in details under the configuration section:
ScheduleTstatZones - Things That Are Smart Wiki.
In your case, you should look into the use cases #10,15, 16,17 and 19.
BTW, if you have many units around in your house, you can use one master unit (ex. the LG mini split) and all the other slave units will be synchronized with its setpoints. With the virtual zone device that you can instantiate under ST, you can easily set a temp delta for each zone vs. the main thermostat’s setpoints (cooling/heating).
The smartapp uses the concepts of zones/rooms/schedules to control all the units (using the room/zone thermostat in each room). If an unit is outside the scheduled zones, then the smartapp can turn it off till its associated zone becomes active in your schedule.
There is more than 4K lines of code in the smartapp as it supports many features.
You can’t reproduce this kind of logic in webCore or any rule engine as those are only good for simple custom logic.
P.S. I’ve also included some special logic for the Remote ZXT-120 (custom DTH) in order to control the fan speed based on the temp differential inside the zoned rooms. I posted some infos about ScheduleTstatZones smartapp in the Remotec ZXT-120 thread about a year ago…