I'm looking into the potential of leveraging existing wired sensors and the Ring Alarm Retrofit came up a few times in this forum. It sounds like it may work for my use-case but I see on the Compatible Devices page that it requires a C7 hub. Is there a technical reason for the requirement on why it won't work on older hubs?
Because Ring requires S2 for alot of their stuff which the C5 doesn't support. Have you looked at Konnected?
Konnected was my other option but I liked the idea of keeping all the Hubitat devices going over Z-Wave and not a mix of Z-wave, LAN, wifi, etc.
Most of us use a mix. Personally I use Z-wave, zigbee, Clear connect, and wifi (Lifx bulbs, 100% local) As long as it's 100% locally controlled I'll use it. Konnected is 100% local and directly supported by Hubitat...
As do I, the idea of the simplicity of a single network for 'security' devices was nice to eliminate possible points of failure or interference
Envisalink 4 is another good option for wired systems. It uses a 4 wire connection like they keypads and let's you bring in all the zones including wireless. Been using it for about 2 years now without any issues at all.