I have grown to really like the VE line of thermostats. I have Helix, Herpstats and VE's in my reptile room. I like that you do not have mount VE's to anything, they stand on their own and are stackable. Currently, I use VE200's, Herpstats and Helix's as proportional termostats on all of our ball python racks, but every single one of them is backed up for safety with a VE 100 (on/off).

I've read that when a proportional thermostat fails, it fails open allowing full current. When an on/off thermostat fails, it fails closed or in the off position. So by using one of each on each rack, I feel I've minimized risks.