Elk/Thermostat integration - current "state of the art"?


Active Member
I've done Elk thermostat integrations in the past using RCS and HAI devices.  Hoewever, in looking at RCS, they no longer seem to have hardwired stats and I see no other hardwired stat options for Elk besides the Apirlaire and HAI.
The use case I'm looking to solve is two neighboring buildings, therefore two HVAC systems that will require two independent thermostats, which already have a shared M1 system between the buildings.  
I mention this becuase it appears to rule out using HAI stats which are RS232 based and would require an XSP in each building, resulting in non-consecutive stats in the M1.  Unless I misunderstand, XSP1 would have stat 1 and XSP2 would have stat "4", which may be an issue?
While I'd prefer a hardwired solution, I see more happening in the wireless stat area.  Does anyone have any thoughts on a multi-building, multi-stat wireless solution that would integrate well (no polling) with the M1?
Thank you all.