Well the M3 sedan is still slower and the acceleration figures and lap times you posted might not look like much on paper but in real life it's very visible. So you can't really say that the E90 M3 is just as good as the Coupe because it isn't. Further more the Coupe probably feels a bit more nimble because it's lighter and has a lower center of gravity. So there is no credit due here because like expected the sedan is slightly inferior.

Just look at the E63 vs E55 battle, on the paper the difference is small but from the drag races we have seen the E55 pulls steadily away from the E63.