Sadly I haven’t had the pleasure! But your assertion is right! The clamping force of the 600 series is dramatically higher than the 500 series. It’s a little like the difference between the Pro and Premium versions of Beyerdynamic headphones.
That clamp makes the 600’s less comfy for many users…at least until they decide to risk bending the headband on their $300+ headphones!
Thanks for reading and for the comment.