I incubated at 86.6-87ish and was happy with the results. The eggs pipped at 62 and 63 days and they all came out with no issues, no egg sack, etc. I think people have checked the temps/hatch time on maternal eggs and they are closer to that range. People up the temps to speed the process a few days and when I read reports of babies coming out deformed, egg sacks attached, umbilicus attached, underdeveloped, etc. the person usually cites a higher incubation temp. Lots of resources suggest there is more risk in overheating than underheating the eggs so this is another argument for leaving a little 'wiggle room.' They are very fragile as embryos and small babies and I'd much rather give them a little more time to develop slowly. Science proves that heat can disrupt cell division as well - which is obviously happening aggressively in a developing baby.

/2cents