We used maternal incubation last season and will again this year, and our temps are lower. 85F is pretty much the highest, and we had no issues. We saw hatch times ranging from 60 to 79 days, and hatchling weights ranging from 75 to 91g. I do agree that the 5 degree swing is too much though. My theory is that the eggs can tolerate a wide range of temps, as long as the temps are fairly stable. I think its the big fluctuations that cause problems. IMO, that is partially why people seem to have more trouble with the smaller incubators. It takes a short amount of time for a big fluctuation to happen.