My only concern with a std GTI would be that it struggles putting the power down in anything less than nice dry and warm roads, whether that just the Bridgestones but am sure the PP is much better due to the differential. I think a remap would be great and guess like others have said, you'd get the benefit of the extra power in the mid range. That said, I had a good 45 min blast the other morning round the peaks and Mk7.5 is deceptively quick on the A and B roads.
I seriously think a std GTI with around 300bhp wouldn't get off the mark much quicker due to traction issues.