Are you coming over to the Nurburgring too (during the AO Nurburgring week-end) in May (or earlier) ? If you do: we can try to make a comparison
I'd imagine your 444 laps of the 'ring might have more to do with how quick you are than what car you are driving
, personally I have been quicker than many a petrol turbo of similar configuration and power output around numerous racetracks as well as a few that were a lot more powerful, only loosing out typically on long straights where the petrol power advantage and gearing comes into play.
I wouldn't underestimate what fun can be had in a diesel, I've certainly had plenty, I have been looking to move back to a petrol mostly for the aural experience and outright speed on trackdays, its quite annoying to batter someone all over the fun bits and get blown away on a straight, I have to say though a lot of the cars I have driven as replacements just don't seem good enough over what I have to warrant changing and I have to look for some proper fast cars that deliver on the speed sensation as well as being genuinely quick.
My GT JTD has been one of the biggest suprises out of anything I have owned and I have had quite a few good motors in my time, most have had similar if not more levels of modification, I guess the suprise probably comes from my expectation of the car, I bought a diesel through necessity rather than chioce, it was a diesel and it looked nice, being a petrolhead I wasn't too bothered how it drove, it was bound to be rubbish in comparison to what I have had before because its a diesel, I took it on its first trackday mainly because I had paid for it months beforehand when I had a GTA and it seemed a shame to waste it, the GT raised a few eyebrows that day and my whole view of the car chnaged as I was blasting past all manner of icons, I didn't even have the good Alfa diesel engine.
They are not bad cars, really, some people especially on this site are just too blinkered to see past their preconceptions.