Join Date: Jan 2012
Location: Plattsmouth, NE
It's a very good idea to have a backup in case of a thermostat failure.
Some thermostats (such as the Herpstat) also have high and low temperature alarms that will alert you in case of a heating device failure. Better thermostats are designed to always fail in the 'off' position, for safety.
When it comes to thermostats, more expensive isn't always better, either. Johnson and Ranco thermostats are fairly inexpensive, but have a good track record, as does the Big Apple Herp thermostat. There's a general distrust of ZooMed devices, but no major issues reported. Among the more expensive proportional thermostats, Helix and Herpstat are the front runners, while the new Vivarium Ecosystems thermostats have a lot of chipset issues being reported.