The other thing that makes a difference is if you are having a new system installed then you can set up zones in the old fashioned way with pipes. So we have seven zones in our house, one for each upstairs floor which are rads, then the UFH on the ground floor is set up in 5 zones. Each zone is controlled by its own thermostat, with nest on the top floors, the UFH is just using old fashioned on the wall thermostats as I couldn't justify putting 5 more nests in... But I am tempted to get some of the cheaper nests when they come on offer to control the UFH, if only to avoid having to set the timer on the old school thermostats.
The other thing that makes a difference is if you are having a new system installed then you can set up zones in the old fashioned way with pipes. So we have seven zones in our house, one for each upstairs floor which are rads, then the UFH on the ground floor is set up in 5 zones. Each zone is controlled by its own thermostat, with nest on the top floors, the UFH is just using old fashioned on the wall thermostats as I couldn't justify putting 5 more nests in... But I am tempted to get some of the cheaper nests when they come on offer to control the UFH, if only to avoid having to set the timer on the old school thermostats.