i agree the 3.0t engines are a masterpiece with a lot of potential, have also driven an S4 B8 which was close to 420hp and it was fast, no doubt about it but it still misses the grunt of the V8/V10.
So you could say about the 2.0T which pumps out now close to 300hp on the R and the new S3, i had a '12 GTI stage 1 and there's quite a few running close to 350-400hp on GTI's and R's, they are good engines with great potential, but the feeling you get from a proper twin-turbo V configuration engine is totally addictive and apart.
Good luck with your debate but i think once you'll drive the C6 and get a bite of that monstrous torque you'll be sold to it, i think you've already done that so we pretty much know what's your next car