Since I am getting no response from other thread, let's put things differently.

What would be the best way to control a 2 temp system?

Trinity Ti100 has it's own Sentry 2100 unit, but alone it will do no good for more than 1 zone.

Primary loop with a 009 pump and then secondary header with 008 pump and manifold for high temp and branch with I-series 3 way setpoint mixing valve, 008 pump and manifold.

I would appreciate advice on what control panel and what thermostats to use, to make this system most efficient. Too late for slab sensor though.

First floor has a thermostat that does central air. Worth replacing it with 2 stage H, 1 stage C thermostat that would do both warm air and radiant? For me it makes sense only if warm air is activated only as emergency, at ~50F. Don't need it for faster temp gain since I don't plan for setbacks.

Or go with dedicated radiant thermostat there?
Second floor need dedicated radiant T-stat.
It would be great if first floor T-stat could program and control both zones.

Taco or Tekmar controls? NT series Tekmar thermostat or something simple?