Alan,
At higher temps than recommended, they become stressed, especially since it is recommended that a SH tank have significantly less water movement than a reef. Less water movement equals less O2 in the water, so there's that problem to contend with too when temps are higher than recommended. With stress, they are more susceptible to infection and disease, such as popeye for instance.
Remember, temps in SHs' natural habitats are fairly stable as they are often found just offshore in, well, this is the wrong term, but in reedy areas where there are plenty of places for pods to reproduce. And of course, different species come from different geographical locations, each with their own temp ranges. However, the three main temp classifications are tropical, subtropical and temperate. Some temperate SHs have a low temp range as cool as 62F.
Overall, though, I don't mess with going to the high end of the recommended temp range. I start to freak a bit when tank temps in summer reach 76F for our whitei (temp range 72-77F) and the air conditioner goes on ASAP. In summer, I keep a constant supply of SW ice cubes in a sealed container in case of temps occasionally going to 76-77F. I add enough ice to cool the tank a degree or two, then the AC does the rest.
Doug,
Please don't look to me as a source of information on raising fry. I did it poorly. Plus, rearing food to feed the fry and keeping fry bowls clean and ammonia free takes up almost your whole life
Only if you have lots of time, dedication, space and money is rearing fry a worthwhile venture.