I have to agree with Wodens on this one Leo, you do ask the same questions over and over again. Not just on this forum, but others as well.
I think just like anything else, there are various ways and means of achieving a goal. SCUBA diving, you can go PADi or the alternative. Shooting, you can go BASC or CA. For obvious reasons there is never just one choice on how to train for something (generally anyway).
Think of it this way Leo. If you want an extension on your house, you get a few quotes, meet a few tradesman and make your decision that way (I'd hope you don't just take the first that comes along - unless recommended of course). You then need to factor in things like cost, general feelings on meeting the tradesman, seeing a portfolio or existing work. These are personal things that only you can decide with.
Ultimately, the decision is yours. In a sport with various routes, only you can choose which road to go down as it is based purely on personal judegment (for want of a better word). Asking the same question over and over isn't helping you. Get out there, meet your BHPA guys and talk to them, see them in action. Then go see Simon and the other instructors at Lambourne and the PMC, talk to them, see how they operate. Factor in everything and you will end up with a decision.
We can't make your mind up for you. Obviously, you ask a hardened BHPA member - they will say BHPA is the only route to take (otherwise they'll be going it on their own). You ask Simon, Norman or anybody else PMC and they will be a tad biased just the same. Similarily, you go to one part of Glasgow and say who should I support - they will say...RANGERS. If you go to the other side and ask, CELTIC would be the reply.