fonseca_323i - You're gonna get some differing responses to this one. The 7.5" pads DO vibrate a bit more, especially at speed 6. Some of us don't mind a bit. You won't know until you try them. I myself find the larger pads easier to use (and I like using the protruding edges for tight areas). It's NOT like you're more likely to "mess up" with one or the other.
Like russ968, I like the Griot's 6.0" orange pads (I often use them instead of CMA white), but with clearcoats you're often gonna want something more aggressive. So have a yellow cutting pad or two on hand, lest you spend forever with marginal results (I'd get the 7.5"). Have some CMA white (either 7.5" or 6")/Griot's orange for a follow-up. Griot's red "waxing pad" is similar to CMA's gray finishing pad. The gray is a BIT softer, but it's not gonna make any difference and the Griot's lasts longer (in my experience).
Note that while I said "CMA," you can get them at TOL cheaper.