I got carbon black and never regretted it. It actually doesn't look that bad with a bit of dirt (aside from the wheels which is a problem for all). However, I do wash it by hand (don't like those automated brushy car wash things) so don't get many swirls. Also wax it every3-4 months which keeps it nice.
When it is clean though, it's cool as f**k in the sunlight. Not that we're getting much of that in sh11ty England at the moment.
Depends on your choice, remember carbon black is a M-sport only colour, and thus rather unique in the range. Black I wouldn't get, it's Carbon or other colour. My GF said white is cool, but I think that's for girls (oh oh, here come the flames ...)
Why don't you just take the leap, and call by one of those handwash car places every week or so?