I would definitely have to say that sticking with the disdain is the best idea. There's a reason Shakespeare wrote it like that and that's a reason I'd hate to loose in the play. You could certainly rework it to fit modern context, but you would have to find a disdain, so to speak, that would mean the same for your staging and your audience. If you were to stick with a high school setting and have primarily high school viewers, the dynamic between the nerd and the jock and the cheerleader would hold the same meaning as the Christian/Jew dynamic in Shakespeare's time. The Moor's "other-ness" would be translated into a typical high school stereotype that fit.

I think the main idea here is to keep the feeling, keep the notions. A play should have meaning and should leave you thinking, so the class gap and class issues cannot be downplayed. I think that's the worst possible thing you can do to a play. The Christian and Jew relationship was a BIG topic in Shakespeare's time, and the equivalent, whether reworked or not, needs to be equally as big.