I haven't heard any evidence that rheostats fail more often than thermostats, and the Barkers (VPI) actually recommend them in their book. You would have to spend the money to get a decent one, but don't assume that you need a thermostat. Do your homework on each, because they have slightly different functions, and choose the one that suits your needs. I'd say that rheostats are better for breeding, and thermostats are better with fluctuating temps and younger snakes that do not need to be cooled. Thermostats (in my reading) seem to handle greater wattage = more tubs.