This mouthpiece is, without a doubt, the best I've ever played.
I have tried quite a few mouthpieces and so far this one offers best endurance, best tone, best range and best flexibility. There is something about the rim shape that makes me want to play for hours, just wonderful. As for the tone, it does exactly what I'd like it to: soft and round tone but opens up nicely with more air.
Granted, this is not a cheap mouthpiece but worth every penny. Comparing it to a Lotus L cup (which is in a similar price range and also a great mouthpiece), here I'm getting slightly darker tone but waaay more endurance.
Note: I used to play a lot on a Bach 3 and this one in theory is smaller but the rim diameter is larger (16.4mm here vs. 16.3 on Bach 3C). In my opinion it's hard to say which one is larger because the rim shapes are very different. Here the rim is definitely less sharp on the inner side but wider.
As an added benefit, I really like the looks of this mouthpiece: classic but with a slight twist on the shape. If a version with a gold rim becomes available, I'm definitely buying it.