any kind of electrical equipment can pose a fire hazard when used INCORRECTLY. your microwave can be a fire hazard; your cellphone charger could be a fire hazard. the important thing is safety and some common sense!
any heating element that is properly regulated and not touching anything flammable is safe. i have used both RHP as well as UTH + CHE and you just need to use basic safety measures (regulation, not touching anything).
i apologize for chiming in without owning a NPI but i figured i could help answer your other questions. CHEs are better at not drying out the enclosure compared to IR bulbs but you will need to do some daily misting to keep things in the correct range. if it really becomes an issue, some sphagnum moss or a damp hand towel placed in the enclosure/on top of a hide should provide enough humidity. these are well-made PVC enclosures so i wouldn't worry too much about losing humidity with either option you choose.
if the enclosure supports it, absolutely go for the RHP instead of a bulb. many headaches will be saved using an RHP.![]()