Mr. Overfilter
Aquarium Advice Freak
I have a finnex, it was recommended for its ability to hold at 82-84 f. It did for a week and than didnt. I use it in a smaller tank to hold 75-77, it does. Actual temp vs dial setting is 5* off.
Based on I've heard here and read, I've been lucky, neither of the 2 800W units I've owned has varied more than -1 degree thoughout, before snapping on.