Thanks. I actually posted on both a Merc and BMW forum because I knew I would get bias feedback.
Your breakdown seems very consistent from what Ive read so far. The thing that amazes me about the M is no tuner has been able to crack the ECU. The Merc guys are getting crazy numbers from just a tune. But your right that is only part of the story, the handling is a little more important to me as I enjoy corners very much. The engine in the Merc seems to be a better overall engine, the exhaust note is better but the handling and transmission are better in the the M. Interior wise is sort of subjective. When I sit in both cars the M feels so much bigger. I like the Merc seats and the simplicity of the controls but I like the HUD and tech in the M.
At this point I havent driven both yet but I am leaning towards the Merc. Partly because I want to try something new. Ill go drive both and see how I feel.
By all means brother, do as much research as possible...this is a big decision, and an expensive one at that.
You're right, as far as interior layouts, subjectivity plays a big role – in general, I feel that BMW tries to find easy ways to make things hard...some things just looks over engineered. In comparison, Mercedes keeps it simple and straight forward...more user friendly...even their owner’s manual is easier to follow.
Handling wise, yes, the M hands down is much better. But remember, BMW’s in general, especially the M cars are dedicated more towards handling vs. overall comfort…comfort wise, Mercedes takes the prize. You can always lower the E63 and gain better overall handling, but with a little ride stiffness penalty…not too bad though.
Tuning wise thus far, yes, the Mercedes boys are doing great things over there. Again, I go back to my previous comment, BMW for some reason has to make things harder. However, tuners will eventually crack the safe…it is a similar battle going on with the new 991 911 TT/TTS P-cars.