I think our moderator (above) made a great point as far as the IDrive.
As far as the S2, I would have to say that it's elementary that a V10 is in most cases going to outpower a V8. In the case of the S2, I don't think that the E60 is going to "crush" it. I think it will be nominally faster, especially from 100 mph and up. Some points that I'd like to point out based on the comments made:
Firstly, the approximately $115,000 that one must pay for a complete Dinan S2 ($80,000 stock E39 M5 price + $35,000 Dinan modifications) is probably close to the price that the forthcoming E60 M5 will cost. I think everyone has pretty much concluded that the E60 M5 will cost considerable more than the E39.
Secondly, I wonder whether it would be more appropriate to compare the Dinan S3 M5 (which, if I'm correct, is still not out) to the E60.
Just some thoughts. :typing: