They're a 343mm/4-pot caliper.
I've also got braided hoses and track pads all round (no squeaking either, thankfully) plus Motul RBF600 fluid. It still seems pretty 'flat' on braking, unless it's from very high speed and then it can get a little nose down, no fade whatsoever so far. As the rear discs come to end of life, I'll change them for some R32/S3 ones to bring the balance back... but I don't feel the need to rush yet.
You can get a 365mm/6-pot MKII Audi TT kit (about a £240 premium), but I couldn't find out if it would fit a Golf properly. I don't see why not though?
I think if I'd have gone for the bigger fronts, I'd have had to do the rears straight away. Just personal preference, but I don't like tail happy cars under braking... some people find this a plus point though, depends on your style I suppose?
Oh, and I'm not painting them - can't be bothered!! Might match up the rears when I get them though.