I dont want to say one way is better than the other, but I CAN personally say that overhead lights/CH's kill humidity wayyyy more than two UTH's do. I have tried both. I Also have two zoo meds, they are good UTH's but yea they do require the control.
The zoo med rheostat I actually just ordered on ebay (it was 9 bux , why not right) so I'll give it a try but right now I have two lamp dimmers, which are basically the same thing. They do require a bit of tweaking almost daily but its better than frying your snake. With any luck the zoo med rheostat will be a little more steady than the lamp dimmers I use. Eventually I will invest in a helix or a ranco to control the heat automaticaly.