If you decide to use an RHP, Remember that radiant heat warms an object, not air. This means that they can create a great basking spot but many new users do not understand the way they work and think they are not producing heat as they should even though the panel is running too warm. The thermostat probe should be placed directly under the panel and no more in most cases than 2" away. Closer is better in some situations.
If you will think of the sun on a 70 degreed day, you will get the idea. If you sit in the sun, you may get too hot. In the shade it will be much cooler. Substrate acts like grass and will not warm up under the panel but dark stone or your animal will. Think of asphalt vs grass with bare feet a sunny day. The grass will be cool in the sun and asphalt can be uncomfortably warm. Asphalt in the shade does not warm up. This is also the reason that the probe must be directly under the panel to control it correctly.
The panels also have a range of about 2', so in a taller cage they are only really useful for arboreal species. If you want to raise the ambient cage temp, placing a section of slate or there dark colored stone directly below the panel can help since the panel will warm the stone and it will in turn warm the enclosure somewhat.