I was just thinking this week how awesome the gearbox is in the GTD, the combination really is a pleasure to drive (and when I say drive I don't mean sitting in traffic!)
The torque is brilliant, and the engine revs much freer than previous diesels I've driven. It's just a great overall package.
As Monkeyhanger says, Trevor is probably a must have one day. I still haven't taken the leap, as the GTD is definitely fast enough for me, but I will one day as it does sound incredible to drive. First service in a couple of months so might add it after that..
Comparing to the GTI is definitely trickier, and your situation an intriguing one! I chose the GTD based on overall costs, but didn't feel like I was compromising as I love the diesel style of driving. I don't remember all the figures, but based on the improved depreciation, fuel and tax, I was saving £100 a month or so over the GTI.
In your situation although you will pocket savings on running costs (unless you were only doing very short journeys!) I don't know if you will be making savings on ownership, based on how your cars are financed, and if you are losing out in the overall early trade in.
So it (probably) comes down to, what you fancy! If you fancy the GTD, I would say go for it. It's an awesome car, and probably slightly more of a wolf in sheeps clothing than the GTI - which may explain why a 1.2 Colt kept trying to race me last night
