Most in bathroom heating is infrared as it heats objects the radiation hits rather than the whole of the airspace. They are more efficient as they are only used when someone is standing under them and then turned off…could be around 5 or so minutes. Airspace heaters which warm the air would need to be run some time to heat the bathroom and then maintain a warm temperature. This could be some some time compared to that of a IR heater. Time of use is where the efficiencies lie.
There are many types of IR heaters such as panel or more traditional ones which incorporate fan, light and IR lamps like this one…
The advantage of more traditional type IR heaters is they incorporate an exhaust fan and light, and the IR globes can be replaced at their end of llife (cost about $5-10 each to replace).
The disadvantage of IR lamps/panels is that they don’t heat the air and the air within the bathroom can still be cold even with the lamps on.
Choice could possibly review them as you suggested, but is may be more about their effectiveness to warm when staying under rather than efficiency, as efficiency is less relevant for such products.
