Read the instructions the heater comes with, and don't put it close to any other objects, or where anything could fall on it, etc. They can get very hot and can be a real fire hazard if used carelessly.

If you have only one snake in one tub though, I'd strongly recommend just heating the tub. RHP's are the best IMHO. They're sort of expensive up front, but they are cheaper than heating a whole room with a space heater for the whole winter every year, or heating your whole house to a higher temperature. An oil heater is typically in the range of 1000-1500 watts. It probably won't be running at full blast, but you can figure that it will probably cost between $10 and $30/month in electricity, not counting the price of the heater itself. With a radiant heat panel you'd easily heat your tub with either a 40-watt or 80-watt panel; in other words, somewhere between 1/20th and 1/10th the power consumption. That's a really big difference. You can mount it to the lid of a tub really easily, all you have to do is put a piece of wood on top of the lid so there's something that can hold the screws.

Another possibility is that you can also use two UTH's on two thermostats set at two temperatures, one for the cool side and one for the warm side. You can even stick a UTH to the side of the tub instead of the bottom, in which case it will actually do more for the ambient temp in the tub since it isn't covered by substrate. Also, insulate the tub.