I was a long time Insteon user that is about to start over again in a new house. Any suggestions for compatible alarm systems through a node server? I really don’t want to spend the money on an Elk. I had heard the DSC Powerseries alarms were at end of life. 

Since 2018 I have been using a Honeywell Ademco VISTA-21IP Control Panel w/Onboard IP Communicator with the add on EyezOn EnvisaLink4 connected via a node server to a ISY994. Worked flawlessly. Can manage through Web, Phone app or UD app. Added UD programs to turn on all lights if there were an alarm and set Thermostats to away schedule when Alarmed Away. Another program to return Thermostats to normal schedule when Disarmed.

Migrated to EISY a few weeks ago. Running good so far. Node Servers can now be run on the EISY under PolyGlot making it simpler. Nodeserver plugin: EnvisaLink-HW

Note: You may not need the Vista IP model as the EnvisaLink4 connects like keypad and provides the ethernet connection. The Vista IP was used to connect to Honeywell Total Connect Monitoring at one point then disabled.

Also EISY and EnvisaLink need to be on the same local LAN network.

Same as above, Vista 21IP, EnvisaLink4.  And, same in terms of used to use the IP module for Total Connect, got rid of that part some time ago as well.  The only shortcoming that I have hit is that the Vista panels stop reporting sensor activity when the alarm is armed in any state.  So, night, stay, away...you won't get motion, door/window, etc activity reported to IoX.  Not a deal breaker for me....the couple of spots that I needed that info I've just used insteon or z-wave modules to supplement.  

Thanks for the feedback. I’ll likely go that route. 

Elk?  Old school but very capable. On my 3rd home install with them. It gets expensive quickly though. The Elk Nodeserver is top-notch.

I went the Elk route before and just personal preference, but didn’t like it. I had an HAI Omni panel at my last house and like it much better. However with no direct integration with the ISY, I was using hardwired I/O to read status or send it commands. Didn’t love that, but it worked. Without seeing any mention of the Omni panels with eisy I wanted to explore other options. 
 

The envisalink node server not reporting zone status changes when the system is armed is my hesitation at this point because I did use that for several things, and not super excited about having to add Insteon contact switches on top of it.