Steve,
I've had diesels and they simply don't excite me like the petrol GTI does. Sure they are good with fuel, but they don't stir the soul like the GTI does. GTI wins for me any day over a GTD.

R32 v's New Golf R - The new Golf R by a country mile - lighter, with more power, better handling and cheaper to run than the R32. Styling, the R32 looked odd with the chrome front and the new R looks better, but still not as good from the front as the new GTI.
GTI v's new R - Is the R worth 5k extra - yes!