I'm using this on a Yamaha YEB-632 EEb Tuba.
Straight away, I noticed a difference with the mouthpiece. I was originally using a Denis Wicks 2L, which is a great mouthpiece, but I was looking for something to use for the orchestral scene. This did the job brilliantly, really good low register (which I wanted as I was playing CC tuba parts on my EEb, so they tended to be very low). The high register is also fine on this, but I still use my Denis Wicks 2L for solos, however I use the PT 50+ for brass band also. It is a really universal mouthpiece and I would highly recommend. The plating on the shank has worn off slightly, but that's to be expected with very regular use. I play around the semi-professionally level, and I would recommend this to anyone and everyone.
It has very good volume, I noticed the increase immediately, however, the mouthpiece is large for and EEb and on the low register notes it will take all the air you can give it, so make sure you've got good lungs.
All in all, absolutely brilliant .