The M6 BMW does nothing for me. The handling that the E39 v8 impressed me with is no where to be found on that old dog.
Take the 500, it probably don't handle any better than the M6 although the propensity to shake is way less with the MB. The MB will handle those monster tires that have to go with either package better. Until the E39/38 v8 suspension (for some reason the E39 6cyl is totally different) all BMWs were rather wobbly.
Bosch Master, ASE Master, L1
33 years MB technician