I used two on/off Ranco t-stats for years when I kept multiple ball pythons in boas in a rack system. They worked perfectly and I never had an issue with them. I kept 10 tubs running just fine. That said, you're always going to get what you pay for - the proportional thermostats are always going to be better at keeping your snake at a steady, constant temp. But for a single tub? On/off isn't a bad deal.