I own three RHPs now they are great replacements for UTH panels they perform the exact same way. If your ambient air temps are cool you will still need something to change the air temps.

Radiant heat does not heat air any better than under tank heating does (UTH) it may add a degree or two that is it. After testing for 3 months I am able to say that the largest difference was 1-3ºF Hardly any help at all. Be well aware that the gain to air temps is minimal. There is a small gain but hardly worth mentioning especially in an open top system. I would recommend a tank on its side with UTH and lights it is cheaper and will actually effect the air temps more than a RHP. Warm and humid air rises and escapes altering the tank to the side holds more heat humidity and has a bonus of actually increasing the air flow in the enclosure.

The manufacturer Reptile basics states this in the FAQ...
This Infrared Heat tends to heat objects more than the air, much like the natural sunlight outdoors...
http://www.reptilebasics.com/radiant-panel-faq


Electromagnetic waves travel through space, it is caller radiation. When these waves come in contact with an object, the waves transfer the heat to that object. From my grade 10 physics book.

Convection heats gasses and liquids like a wood stove not like sun in through the window in a cool house in the sun it is warm as soon as you step out it is not. Radiant heat does not heat air. UTHs do not heat air they are the same type of heat suggesting that a UTH heats air is the exact same as suggesting a RHP does.