IMO you can never go wrong with added warmth in a bathroom so just install it and if you don’t need it don’t use it. There are lots of nice heater, light and fan s to choose from.

Is your radiant heat electric or hydronic? If electric, is there not a real source of heat in the room?
Note that electric floor radiant heat is not for heating a room, only for warming up the floor.

are you putting the radiant heat under the shower floor too? Cover the entire floor, not just the traffic path. I don't live in a cold climate, but do have a radiant heated floor under tile. we leave it at 72 year 'round.

We have a whole house with radiant floor heating. In the bathroom we have a small electric tower heater. Depending on the temperatures we just turn it on a few minutes before we want to have a bath or a shower and by the time we are out of the water it has heated up the room to a lovely temperature. Easy to have and use.

Do not put heat under the shower floor:

1) Electric mats can develop defects and the presence of water can lead to a shock hazard. If you think this is far-fetched, there is more than one thread in these forums about such problems.

2) Hydronic heat (warm water circulated in tubes) does not present a shock hazard, but it is also of little use in a shower. Radiant heat only makes the floor warm enough to keep the ambient air at a decent room temperature...as soon as you turn on the shower, the initial blast of water overwhelms any contribution of warmth from the floor in a second or two.

Thank you to all how helped answer my question. I should have been more specific and indicated that the heated bathroom floor will be hydronic. You are all so kind to take the time to help educate us!

I have had heated bathroom floors since the 90's. Always been electric, never a problem. My main bath is now 28 years and still works. You lay it almost over the whole floor but not under toilet and floorstanding vanity. The heated floor help the shower to dry faster and no risk for mold.

With the hydronic heat, you will probably not need a ceiling heater.

My whole house has hydronic radiant heated floors, with each room its own thermostat. We have found that leaving the master bathroom set for 75F and master bedroom off provides the best comfort - the overheated bath heats the bedroom sufficiently and that nice warm floor is a joy for those nightly visits. The exhaust fan has no heat (there's no intake fan). (No radiant under the shower).

Interesting answers above. I would inquire about what kind of flooring you folks all have. Some mentioned tile in regard to bathrooms, but others said they had whole house radiant. What kind of flooring throughout the home, please?