Overall, a really good mouthpiece.
I have been using it for about 3 months. I play to a professional standard. I moved from a Griego 0.5 to 0.25. My setup is an Edwards bass trombone with a dual bore slide.
The extra dimensions are quoted as being a noticeable change. I straight away did not notice the physical dimensional changes.
My comments viersus the 0.5 mouthpiece: (1) adapting - Minimal time to get used to it. (2) power projection - Similar with both mouthpieces having sufficient/more power than required for most musical settings (3) Depth has the 0.25 adding more, it doesn't add to the lowest note I can reach, but it does thicken the motes immediately above my lowest notes, enough to make this comment (4) A good response to articulation but like the 0.5 the 0.25 has not made this snappier for me in the pedal range in the same way a smaller bass trombone mouthpiece can, and why would it? It is not what I bought the mouthpiece for.
Overall, for what I want it for, a really good purchase.