You shouldn't leave a review until after burn in. As many others have made that mistake, and then corrected themselves after burn in. Give it time.
As for comfort, try laying the headband somewhat flat to reduce the clamp force once in a while, until they start to naturally adjust better to your head.
Also for comfort, for the short while I had the M100s (1 month), it really depends on what kind of ears you have. Mine unfortunately touched the drivers and would give some pain. I later returned it. They should be coming out with bigger earpads later, so hopefully that issue will be solved for people like me. And as for sound, try getting used to the M100s and then go back to your 6000s. And then compare the two.