The 'fast' ones you've meantioned, do you mean elastic loops? Personally I prefer my pots to be securely fastened. Diving in to your primary and lossing a pot or two blows. Plus as a front guy you aren't going to be firing as much as a back guy, so won't be loading as often, and thus don't need to worry about the time it takes to unso a piece of velcro.
So, a 4+3 should cover you. If you only want to take 4 don't use the loops. If you need extra, you've got space.
EDIT and it depends a little on what format you are playing, 5 or 7 man. I'd take 3 pots for 5 man and 4 pots for 7 man.