Is insurance important to you...is so why?

This same logic can be applied to why you might want a back up thermostat. Flexwatt can easily hit 115+ degrees in a few mintues. High enough to burn and/or kill your snakes (or cook eggs in an incubator). If you have $1000s or $10,000s of morphs in a rack (or potentially in an incubator) is $75 worth some peace of mind?

Only you can answer this question.

A backup thermostat is typically set a couple degrees higher than the main one. If the main one fails then the backup kicks in to keep the temps in check till you can replace the defective one.

Now where the question comes in (like in insurance) is it common for thermostats (at least the name brand ones) to fail? No...but some will...are you willing to gamble if yours will fail?