Not to down THG but flexwatt is in 1000s of homes and have been running for years. I remember seeing it years ago for heating bathroom floors, didn't know it was the same company.

As far as testing goes flexwatt has been used over and over again.
Now is it the safest thing for our snakes? I don't know. I'm running both in my home.
Sounds like both products rely on the t-stat not failing.