I enter into this discussion to give a personal opinion different from those who have written here.
I mainly play the euphonium, the baritone I use it mainly for marching services. When I purchased it, a few years ago, it came with a DW 6BS mouthpiece. I tried it for a while but I understood that it would not work for me: the tone I get is good, but it's top small, I can not make my chops vibrate properly, especially in the low register, and its narrow border limits the my stamina, so I bought the K&G 4B, the biggest measure they have for baritone. This mouthpiece has a shallow cup which gives a sound top light that I do not like at all, moreover I still feel too small, so I bought a piece for trombone, the K&G 3C (I wanted a D cup, deeper than C, but it is not produced with little shank). This mouthpiece met my needs for support and size, but it still did not give me the sound I wanted to achieve with baritone, so I decided to personally modify the profile and depth of the cup. The operation has an extraordinary result, much better than I could imagine: I got the perfect mouthpiece ( for me) for the baritone which I also tried, with an adapter, even on the euphonium with satisfactory results. This new prototype, compared to DW 6BS, has a wider cup( 26,4 mm vs 25,4 mm), a border wider than 1 mm, a large throat (7,2 mm vs 6,6 mm), while the depth is almost the same. I enclose a photo: upper the DW, down the K&G.
Last edited by franz; 02-10-2019 at 10:41 AM.
2007 Besson Prestige 2052, 3D+ K&G mouthpiece; JP373 baritone, 4B modified K&G mouthpiece; Bach 42GO trombone, T4C K&G mouthpiece; 1973 Besson New Standard 3 compensated valves, 3D+ K&G modified mouthpiece; Wessex French C tuba, 3D+ K&G modified mouthpiece.