We used Nu-Heat Thermostats with our Nu-Heat flooring. Not too difficult to set, and their customer service is good about walking you through setting it up or changing your settings if/when needed, too.

We have the Nu-Heat Thermostat with our Nu-Heat floor as well. I gotta say that half the time I can't figure out which temperature it's showing but it's super easy to set and is working well. Together they have been keeping our bathroom floor a lovely temperature during this cold winter! I had no idea how cold natural tile could be until I had it warmed.

Do you already have the flooring and are just adding the thermostat? If you're just putting into the floor, here's two caveats we learned (fixing the first for our renovated master bath!):

1) If you are putting in under floor for the first time and they tell you it will radiate heat to the surrounding tile, it will NOT. We put the mat under only part of the bathroom floor thinking at least the other half of the tile it was under would warm b/c of the mat. NOPE. You can literally feel the cold on the back half of your foot when you step on the half-on/half-off spot. It is ice cold. So put it everywhere under your floor you intend to walk. We skipped about four inches in front of the vanity in order to not have to buy another piece of the heated mat grid and now we have to stand away from the vanity a little b/c it's cold there!

2) I find that our Nu-Heat makes a clicking sound when the heated floors were going on and off in temp. I don't know if that was the actual mat under the floor or the thermostat, but you could definitely hear it click. It hasn't been much of an issue lately b/c it's been so cold that the floor heat isn't going off all that much but I'm just pointing it out in case that would bug you.

Good luck!

Thank you akcorcoran.
I am definitely paying attention to where we put the heated mat/cables (still deciding on which). Had a long coversation with DH regarding the reasonings why we just can't run one long mat lengthwise down our bathroom. (for the same reason you mention).