Yes, I think it DOES make a difference. When I get a roller set at the salon, I never let them put the dryer on high or put me under that SUPER HOT dryer most little salons here in NYC seem to have. I mean, come on, if they need to put little "protective devices" over your ears to shield them from the heat IMAGINE what it's doing to your hair!
I think a dryer can be TOO hot. I can use my home dryer on high without it burning my ears, but I've come to the conclusion that High is still too hot. I dry on Warm.
If the air is extremely hot coming out the dryer, I really don't see how that is much different then blasting your hair with blowdryers at all angles at once. (Was that clear? /images/graemlins/look.gifSorry, I'm getting tired now.)