Personally,
I'd go for 4 pots. Howevs like if you have a budget, 4 pots might cost you more than you'd like.
For instance,
Moi, second time round...
150 for Calipers collected
40 to paint
20 on custom decals (only used badge)
2-3 on normal decals
Then you'd need
fluids
23mm MC *assuming you're on Brembos*
discs
Pads
lines
fitting if you canny do it yourself...
So far I've spent 190 odd on mine. Still need discs *arguably don't* decent pads, lines & fluids.
Anyway, I agree with what people say about normal brake upgrades. Discs,pads etc can make all the difference.
For instance,
My last set of Brembos,
I got cheap discs *drilled and grooved* and some shit mintex pads. The guy who ended up with my car took the 4 pots off earned some pocket money and ended up with better pads on gti brakes etc and he thought it performed better.
I'd still say, not only do 4 pots look far better, but after decent pads etc they will or at least should outperform the gti's. So much to factor in though I guess... they add weight. Tell you what though, even on shit pads my vts stopped definitely far better than stock...
Anyway. I will stop talking crap now.