I am not sure how much variation and how specific an incubator needs to be. Johnson's have a higher possibility for inaccuracy, they state +/- 2ºF add the 1º set point and you could see three degrees different from where you have set it. Most proportional ones have higher accuracy and so you will see +/- 0.5º shift from the set point. I don't know how much that matters but 3 degrees seems like a lot.