We went for the SE for 2 main reasons.
I wanted the 20" alloys and the ride quality is softer on an SE than it is on a S-Line. The S-line has firmer more sporty suspension (even with dynamic drive) but we prefered the smoother riding SE (I must be getting old
). We like the speed (hence the 3.0TDi), but aren't so worried about "on the limit" handling, but i guess it's a personal choice.
The other reason was that Audi wouldn't supply our car in garnet red with the Cardamom leather interior on an S-Line. We like light coloured interiors and ultimately this was the over riding reason. (maybe this has changed now ???)
We plan to hold on to the car for a good few years... 5 at least, so trade in prices shouldn't differ too much by then.... fingers crossed
Either way, the Q5 is living up to my expectations and it's ability in the recent deep snow has been pretty decent.... 5"to 6" of powder snow wasn't a problem, even on the standard tyres.