I'm afraid I don't agree. I haven't played a PPT or a Gerber mouthpiece but I have played on many others. Recently my alto mouthpieces have been a Jody Jazz DV and a Claude Lakey Rubber. The Lakey is a much more comfortable 'piece for me to play on and I have had it for 30-odd years. It's a fantastic lead alto mouthpiece in a big band and can be a terrific pop mouthpiece but can also be dialled back a long way. The Jody is not so much of a Chameleon but it has stuff about it that I like. The price differential is enormous. I also have a Vandoren V16 which is great for straight ahead jazz.
I also play a Selmer S80 D on soprano - a classic mouthpiece for all styles. Price in todays market is very low. I've also played on Beechler and Dukoff at times in my career. Depending upon what I was playing at the time they were great.
Selmer S80: £138
Jody Jazz DV: £429
Claude Lakey Diamond Inlay: £
Drake Pete Christlieb: £350
Vandoren V16: £126
Beechler Bellite: £365
Dukoff: Now only available as ARB Beechler copy £383 but until relatively recently were very cheap.
Not that it matters, but for reference, among others:
Selmer S80 - Branford Marsalis
Vandoren V16 - Danny Janklow
Jody Jazz DV - Andy Snitzer
Beechler - Marienthal, Koz, Paulo, Rangell
Dukoff - Sanborn, Wilton Felder
I'm not sure if Gerber are even available in the UK. It lists on its website Tucker Antell and David O'Higgins as players of Gerber - both great players but that's it. Same with Wanne - Gerald Albright and Jan Garbarek. Even Brecker didn't convince many of his contemporaries to play Guadala, who we have to thank originally for escalating mouthpiece prices considerably.
I do understand your point, and what I'm saying doesn't really contradict it.
I'm not that familiar with the Lakey alto pieces -- I've had them, of course, but just don't remember them as well as tenor because I played on one tenor for a short period (15 years ago or so) and of course have had clients that did. Objective/subjective observations of the tenor pieces: very powerful, full tone, sort of a different version of a Berg in being sort of a "1-trick pony" (sort of wants to do one thing, and one thing only, less adaptable than subtler and more dynamic pieces), but also very difficult to control (uneven scale, inherently, relatively squirrely/indefinite pitch center, not terribly dynamic inherently, very muscular and not very fine). For the right player, the plusses and minuses will line up, and for that player the minuses won't really even be minuses, but as a general rule for other players than that person the objective/subjective qualities will be consistent across skilled players. If you have a hard time getting the full, powerful sound you're after on other pieces, a Lakey or a Berg may get you there, but there will be performance downsides (on a Berg for tenor, poor subtone is a parallel to poor control on a Lakey tenor piece).
Consistency is also a factor. Contemporary mouthpiece makers in the US$250+ range are (in practice, I don't know about in theory) able to make more consistent pieces than in the past, or than mass production brands (like Babbitt). That figures into my statements above when discussing dollar-for-dollar value. I have to recommend things people can get by mail, often, so that figures into general statements about quality and cost.
Critical remarks are also generalized to general commonalities in what people are pursuing in mouthpieces for alto (most often something in the Cannonball/vintage-Meyer vein, but this is shifting) or tenor (vintage Link). Prices for those pieces (actual vintage pieces) reflect that.
But, sure, people coming from other desires and expectations will want and be satisfied with other things, some of which may be very inexpensive. Rico Metallites are of course the quintessential "cheapo pieces that consistently play pretty well for how cheap they are," but the tone bears discussion whenever you recommend one, because most people will eventually abandon them because the tone's not too awesome.