So more power combined with a dual clutch transmission makes for the result you see here. Now, the cars are fairly close but the M6 takes every race except for one. From a roll or stop, it does not matter. Even in one of the runs from a roll where the CLS63 jumps the M6 is seen catching up to it. So, one can confidently state the new M cars are slightly quicker than the beastly AMG's.
The real battle will be once these motors are tuned and it remains to be seen if the S63tu in the M5/M6 can keep up with the Mercedes M157 putting down some very, very impressive numbers.