I'm curious to see what BMW does with the side vents. They look fine on the e46 M3, but the e90 has such a sculpted body that the e46 vents would look too blocky and maybe even out-of-place on the new M3.
The E90 looks more like a shark. Put the old vents on that shark and it would funny. Maybe shark-like gill slits would look better or perhaps no vents at all.