Yeah the RS7 is a beast for sure but yeah the tranny is a not on the same level as the M. Interior will be better in the Audi, AWD is a nice option for putting down all that power. Looks are completely subjective of course. I like the look of it but I know its a turn off for many.
Thanks for the info on your experience with your MBs. I really like the look of the M5, the handling is much better and it has better technology. I need to go drive the E63 and see what it feels like. Ive owned Audi, (still do) MB and BMW (E60 M5) and have liked all 3. The new electric steering in the Audi drives me crazy but my wife likes the feel of it, so if the E63 is similar it could be a deal killer.
The steering is less numb if you opt for the Performance pkg.
Remember, the E63 is really built more towards cruising duties while the M5 is more more track focused.
I like them both, the M5 does feel more secured around the twisties and high speed curves and give you more road feedback while the E63 will feel really silky smooth and taking you and the wife to dinner a la "rico - suave" with endless torque.
It all depends on what you want. Bottom line, simple summary -the M5 rides harder and the E63 rides softer.
I look at it like this (during his prime):
M5 = Mike Tyson in boxing gear
E63 = Mike Tyson in a tuxedo
*dressed either way, Mike Tyson could provide a heck of a punch, but he'll move better w/o the tux...get it?*
Which way do want your Mike Tyson?