Both have very clear faults. The 650 is extremely uncomfortable, clamping one's head. Also, there is an obvious veil in the upper midrange which was supposed to be fixed from the 600's, but they weren't.
The 7000's (which I love, but still has it faults), has extremely wobbly bass.
One might like the 650's over the 800's (which is a minority opinion, but everyone is allowed to have their own opinion), but the 650's and 7000's are certainly not "fault-free".
The 650 does not clamp after about two weeks. If it does, it can be fixed in seconds by bending out the metal part of the headband. In short, it's not a problem.
"Obvious veil in the upper midrange". Well, if you hear it, okay, but "obvious"? My memory may be failing, but I don't remember, in all the thousands of 650 posts, seeing any mention of a veil in the upper midrange. Upper treble maybe.