ADT/SmartThings Offers fire monitoring for an extra fee in most areas, Scout doesn’t have it at all, so that’s just something to be aware of.
But if you go the Scout route you also have the issue that Your Internet has to be working in order for your security system to work. There’s no cellular communication option like the one that’s built into the ADT panel. And there’s literally no way to arm or disarm the original SmartThings system, even with scout, unless the smartthings cloud is available.
At this point all of the links on the smartthings website for security go to the ADT model line, it’s really the only one that’s suited for being a primary security system.