I've had my JTS for three months now and not once looked back. Given that I'm only 22, the 2.0 insurance was eye-watering enough and when I approached the insurance company about a 3.2, they pretended not to know me... I also drive 60 miles a day and average 32mpg - a statistic I'm more than happy with and wouldn't get close to with the V6. The diesel, although test-driven, was never really a consideration. Altough many people are quick to sing the diesel's praises, the marriage of Italian sports-car looks with London taxi acoustics didn't really do it for me.
Would I prefer the performance of the V6? Probably. Do I feel as though I compromised? I drive an Alfa GT - not bloody likely.