4.2 TDi or 4.2i D3?

[goldsax]

currently have a D2 4.2 2001.
absolutely love the grunt coupled with the Quattro system. and am getting 28-29MPG average.
if the right D3 came up, i would be interested in changing.
the 3.0 TDi on paper looks slower then my D2. is this my misconception?
i am sure you can chip it to increase performance etc
then we get the 4.2 TDi, 8-10K for a nice looked after car.
then the 4.2 petrol 6k for a nice car.
i do about 15K a year, looking to have a car for 2-3 years
i am thinking, do i want the complexity of a 10+ year diesel engine and its potential injector/EGR etc
or look for the shunned and significantly cheaper 4.2 petrol?
cheers raj