Don't take this the wrong way--but the claim that everyone in the grade up is bratty and self-centered seems a little off. I'm sure that at least a few of these kids have younger siblings in the grade below, so all the parents can't be that bad. An entire grade level of bratty kids seems like a gross over-statement.
I often find, when I feel like I don't want to go out of my way to make friends, that I too will make broad sweeping statements about a group along the same lines...ie, all the moms in the neighborhood are too high-maintenance, clickish, etc. But when I finally decide to step out of my comfort zone and get to know people, there is always a lot more good in them. Perhaps the fact you think the entire grade is self-centered, really means that you are just afraid of the skip and that is your fear manifested.
Look for the good in these kids and their parents, and you will find it, and your child will be happier. Good luck!
ITA. Your ds asked for the skip, it appears the school is willing to accommodate the skip - I'd go for it. The parents, even if they are beyond horrid, aren't your ds' problem, and really - he's the one who's having to sit through 6 hours of school every day. Having to put up with obnoxious parents for a few minutes at drop-off / pick-up or an assorted meeting here or there throughout the year seems like a fair trade-off.
Best wishes,
polarbear
