MK7 with PP. absolute no brainer.
You'll buy a 35/R, see a MK7 and read all the reviews praising how awesome it is and hate your car. Irrational, as both are excellent... But it'll happen.
Comes with a diff, far less weight, a very fancy RenautlSport style front suspension and it'll hold it's money far better than the older car. What's not to like?
Early car niggles? Meh, it has a warranty. Tuning? Who is to say it isn't the next 'best tuneable engine ever'.
Oh, and you can still get in an M135i for £27k with discount, just sayin...