Well if I was careful, I'd get just over 40mpg from the 1.8T in a Golf (so admittedly a different map). I hear the 3.2 gets more like low 30s.
I think the point for me is that the 1.8 has such a flat torque curve (which some love and some hate) so it often feel quicker than the V6 without having to stir the gears so much. Yes, when it comes down to it, the V6 is the faster car, but in the 'real world' I would suggest the 1.8 is better. horse for course though!!
What?
I had a 1.8T golf (remapped) followed by a 3.2 DSG TT and you have to stir the gears a *lot* more in the 1.8T. The 3.2 pulls from any gear without any effort at all. There's no way in hell that the 1.8 is better in any way other than economy (and even that wasn't much better, maybe a couple of mpg)
If the OP is going to buy a TT, definitely get the V6 without a doubt. The DSG is great fun......for a few weeks then it becomes a bit boring and you wish you had a gearstick again. It becomes too much like playing a Playstation game so hold out for a 3.2 manual instead if I were you.
When you get your V6, do the exhaust flap mod (takes 2 mins) and also the Wakbox mod (take 15 mins) and you'll get to hear all of that lovely V6 growl everytime you put your foot down.

Later models of S2000 have their own form of traction control as well, with a budget of 11-12k you could find an 05/06 or newer one as well!