what a tough choice!! here's my take on it....
black w/ brass bullets
pros: classy and timeless! it is, after all, the bag that started it all!
cons: most copied/faked rocco out there, doesn't "pop" (but again, not meant to since it's more refined)
black w/ pale gold cupcake - btw, there's no pale gold bullet version, only cupcake

pros: bright and modern; i've also heard cupcake weighs a little less than bullet studs
cons: too "blingy"
this is coming from someone who has the black w/ rosegold combo. this is seriously my FAVORITE bag i own! this is just my opinion, but the bling is totally awesome! i get so many compliments on it and it matches with everything. i think the classic shape of Rocco and gorgeous pebbling really balance out the studs, which give the overall design an aesthetic omph!! if that makes sense!
lastly, i don't think u should let the price issue weigh in (even though that's tempting); i paid full retail for mine and would do it all over again bc it's the exact combo i want!

btw, u did luck out with the brass one - the pebbling is GORGEOUS!! let us know what u decide!