I had a friend who used a Ranco on his incubator. Good thing he woke up in the middle of the night, for some odd reason, to discover it had failed and hi temps were up at 103.
I use a ranco on my rack and it has been perfect up till my wife slammed a bed frame into it and it stopped working till I hit it again. No problems other than that with it though. I may go with a different one now tho.