Bull****! Here in the NE, I know of several boat charters that require advanced certification and more than 25 dives to do the deeper wrecks. For most agencies that 25 dives is implied in the "advanced certification", but PADI is "special" and probably why the 25 dive rule was invented. Try diving the San Diego with 10 dives and a PADI advanced cert and see what the captain says.
Stuart, there is no reason to switch agencies. The easiest thing is to be honest with the boat captain about your experience level in terms of number of dives and/or specialties (don't use card names, just facts like # of dives, where, what conditions, and what training you have taken).
If you are vacationing in the caribbean, they most likely will not require advanced certification because they get so many resort divers in the first place and have DM guided tours. The standards on vacation in the caribbean are much more relaxed and just an OW card will get you pretty much everything you want. The advanced certification is a thing on boats in the US, where a lot of them don't have DM led tours and you are very much on your own.
---------- Post added November 5th, 2014 at 10:08 AM ----------
4 OW dives count.
Dives in a pool do not. Same reason you need actual OW dives to get certified.
Advanced Buoyancy shouldn't be conducted in a pool, and I would demand they take me to some OW environment. The course is really about learning how to task load and task loading implies dealing with full dive gear, cold, limited vis, etc.