I bought an 82Z around two months ago, so here are my impressions Vs my MKVI's.
The palm keys are very high! It was nearly enough to make me send it back to the dealer, and initial impressions in comparison to my 6's wasn't particularly good either - I'll go into that in a minute - but after a few days it was starting to feel much more comfortable and, more importantly, there was something in the sound and response that I was really starting to enjoy.
I completely understand why some people have said they find the 82Z resistant compared to a MKVI, and I also understand the other point of view. It seems to me that Yamaha have achieved something fairly unique with the 82Z - an instrument that can feel resistant (in a good way) and incredibly free blowing at the same time! On a straight comparison with my 238XXX tenor the Z is not as free blowing (ie it doesn't seem to take as much air, or there's more back pressure - ie more resistant) but at the same time it's more responsive! The notes just jump out with less effort, making it feel as if it's less resistant, whereas going back to the 6 reveals that it is - relatively. The difference between the Z and my 121XXX is less pronounced in that way, but the same findings apply. The Z seems to have a very nice solid core to the sound as well as being incredibly responsive from the very bottom to the very top. The harmonics (altissimo) are extremely easy to produce, although they seem slightly less full than on the 6's. In fact the whole range feels less full sounding, but it's certainly not thin either, in the way that I feel 61's and 62's can be, particularly in the upper mid register.
From past experience I know how much difference the neck can make, so I got hold of two more G1 necks for comparison. Whilst there was less difference than I have found between Selmer necks in the past, there were still very discernable differences between the three. I played all three necks to as many people as I could to get feedback and one person, who I managed to victimize on three separate occasions, picked out one particular neck as his favourite every time without knowing which was which (they all looked identical)! Interestingly, the two new necks both offered even more resistance than the original, but in most peoples ears were the better sounding of the three.
So IMO the 82Z is a great tenor. It's not a MKVI, although in many ways I feel it's more similar than the Selmer Ref 54, but it has it's own very attractive qualities. I still wish the palm keys weren't quite as high, although after playing the instrument for a while I don't notice them anymore, and they're certainly better than the palm keys on the Ref 54 which are too low (why they couldn't reproduce the ergonomics of the MKVI I don't know).