They're strictly for looks for 99.99% of enthusiasts.
As for using OEM M3 front setup, we tried that on my car but it didn't work. Something about how the M3 control arm not mounting to the knuckle? I can't remember. Maybe someone more technical can chime in for me.
Imola Red / Imola Red ///M5
E60 SSK, Dice iPod, GT Exhaust
BCR Coilovers, 19x10 + 19x11 Rial Daytona Race, Michelin PSS
335i M-Sport Alpine White / Coral Red
H&R Sport, CF diffuser, BMW Performance SSK
'04 E55 AMG Brilliant Silver / Anthracite
'96 318i Alpine White / Black
'01 330Ci Titanium Silver / Coral Red
'96 328i Jet Black / Black