If you are cross shopping an E9X M3 with an F10 550i, then you don't really want the
M3. Justifying your decision based on subjective "dated" appearance and then making comparisions to performance based on shear numbers between two different classes of cars doesn't have any value.
Sounds like you just want the newest "Bimmer"... so get the 5 series.
2006 Lotus Elise SC
2008 AW E92 M3 6MT - Sold
2004 AP2 S2000 - Sold