Ok, I got one of these-a Doc Tenney Meyer 6M.
To start with I was confused as it was hard to find the right point to place the reed. The table has been filed so that it is wider than the reed. There was a slight bump in the table where the facing had been engraved. In fact, it was hard to get the reed tip to meet the tip of the mouthpiece. I've learned to go by the tip, not the rails for the best response. He also seems to have done something to the baffle (it needs more air low down).
The differences between Meyer type pieces are small. I've recently tried a Barone NY6, A GW5 and a Pillinger NY6. The resin Pillinger stood out in terms of response & is my favourite. Apart from that one, I can't hear differences on recordings between these different pieces.
The sound of the Tenney is essentially just that of a Meyer-there are no quirks and the tuning is fine. I tend to use one mouthpiece for Jazz & classical studies (practising anyway) and so far, this seems good for that. I can get all the overtones and get my low notes with & without my tongue. In a way, there's nothing exciting and that's the way it should be.
It does have that 'new' mouthpiece sound about it, but 10 years of playing it should sort that out. I believe that playing these things does change their feel; like the wood of a violin.
I'd be interested to know what other players have thought.
Jamie O'D.