The issue for me about mouthpieces is: "You never know until you know". If you only ever play one mouthpiece then you will never know whether any other mouthpiece would sound/feel better than the one you start off with. A friend of mine who has a Yamaha 7C mouthpiece, and has been playing Alto for 6 months reported that he was "very happy" with his sound. He came to visit last week and tried all my Alto mouthpieces. It was certainly an eye opening experience the improvement in sound, and he has decided he wants to upgrade his mouthpiece as soon as he has the cash. The ones he tried were Vandoren V16 7m HR & Ponzol Vintage 0.070 HR (others were slightly too large, inc. Rico B5, V16 9m, Ponzol 0.085). The Ponzol was a revelation - his sound was far more characterful, complex, interesting and more. It was an obvious improvement to both of us, with no discussion until preferences had been stated.
This is not a shameless plug for the Ponzol (the 0.085 is my main piece) but rather in favour of trying alternatives and not just resting on our laurels. Similarly most people are happy listening to music on the equipment that they have BEFORE they hear better equipment. So I do challenge the assumption that you should only try alternatives when you are dissatisfied with your current set up in some way - too bright, too mellow or whatever.
The reality is that the original Meyer Alto mouthpiece set the benchmark for jazz players, and many Ebonite/HR mouthpieces are modern copies of the original. In the States you have a number of excellent alternatives (Meyer is generally considered to be not what it was) - Ponzol, Mouthpiece Cafe, Barone, PhilTone, and in the UK we have Morgan Fry, Ed Pillinger and maybe others. If you have the opportunity to try one or more of these - depends what stores you have local to you - then it would certainly help clarify whether a change/upgrade would be a good idea. If you have to rely on Online stores then there are one or two who offer trial periods on up to 3 pieces, and "JunkDude" would be an excellent retailer to address a query to.
On all the instruments I play (sop sax, alto sax, tenor sax, trumpet, cornet, flugelhorn, tenor trombone) I have several mouthpieces and it has really helped me clarify what I need/like/prefer/play so most of them are idle at this time but I am much happier with what I do play now, and I know why!
Kind regards
Tom