Rethinking my Home solutions....


After ~15 years, I think it's time to revisit my HA needs and wanted to get some thoughts with users that have experience in other systems/software packages.
I have mostly been a lighting/HVAC guy because we mostly lived away from our main home & wanted it to look "lived in" and be able to kill the "cold soak" before we arrived in the winter.  To that end, I installed a pretty robust Insteon setup controlled by Homeseer...later adding RCS Thermostats integrated into Homeseer with 1-wire monitoring of the temperatures throughout.
I have few complaints about how it worked...and the complaints were mostly my fault.
However, since moving back, my HS interface is relegated to automatically turning outside lights on at dusk, etc....and support for my thermostats has diminished.  The 1-wire network was always "touchy" and that isn't as important these days. Add to the mix that our alarm system is overdue an update since the alarm company didn't bring it into the 21st century when they replaced it for going "deaf."
My Critical functions are still Alarm, Insteon lighting, and thermostats.  I would like to simplify control of my AV options...Multiple SageTV extenders, AppleTV, ROKU, Bluray, receivers....with interfaces to help the WAF.
Nice to have:
CCTV display integrated (currently have hard-wired CCTV & Blink Cameras)
I am investigating ISY, ELK & CQC to integrate my "problems"
I'm thinking that ISY can control my Insteon Lighting
Elk will be my security solution
CQC can integrate the above, work with the RCS thermostats (two, no zones)
I can use CQC to develop interfaces & work with my media....
Am I thinking correctly using CQC to integrate the parts?  Or should I look at using Elk to integrate the ISY (Insteon) & RCS thermostats...then integrate the ELK with CQC?
Many ISY994 users use the ELK node module and are very happy with the combination, apparently.  Why would one need more than that simple combination?
I only use my ISY for security and have no ELK system, though.
Check-out Home Assistant and-or Node Red. I think the ISY folks have an integration solution called polygot, but I'm not familiar with it.
CQC is very robust and is going open source.  This means you can try it out and/or use it free of charge.  Obviously it will be hard to tell how much future enhancements will be made, but there are plenty of users out there, so maybe things will be added.  It can certainly tie the three systems you have together.  Personally I use the ELK and RSC thermostats with CQC.  For lighting I am using wifi switches/plugs flashed with Tasmota, but that is integrated into my system as well.
I believe you can tie the RSC thermostat into the ELK using on of their serial communication boxes (forgive me, I don't remember what they are called off hand and I've never used on personally) if you wanted to go that route too.