I had a hard choice when I changed my car last year, have always loved my fast Golfs, on my 4th....2 GTI's and 2 TDI's!
I think a lot of people miss the point with the GTD. I'm heavy footed and accept that a carefully driven MK6 GTI is mega economical if you drive it nicely. Problem is, in a GTI I will burn fuel for fun!
Difference is, in my GTD, which is quick and sounds good, I thrash it to bits and it still has an average of 44mpg after 16k miles! Simple fact is that it saves me at least a tank of juice a month at £60+ a pop. Of course people will say...I can do 35, 40, 45 mpg in my GTI but thats not drivin like I drive car!!!!!!