Ref,
I've great respect for the osteopathic tradition. I think it encompasses far more than OMM, and those who advertise osteopathy as "like a regular doctor, but iwth manipulation" are doing it a disservice. I find the osteopathic emphasis on what I think is better termed "frontier medicine" than primary care important and necessary.
AT Still was ahead of his time in arguing that every dysfunction is essentially mechanical, and he did pretty well with the tools he had. Now our tools are far more finely honed and many happen to be in pill form; I see no substantive difference between a drug and a manipulation; both are intended to correct or lessen structural defect.
With that said, it seems pretty clear that OMM is preferable to drugs in many instances, particularly when treating pain. There are some pretty good studies supporting this. However, there's a lot of baggage attached ot OMM that has absolutely no scientific validity.
The problem with OMM instruction is that those most attracted to it tend to be the least skeptical, and though a lack of skepticism is great for a faith, it's awful for a science. OMM fans have been more or less left to their own devices for the better part of a hundred years, and the result has been a lot of hypothesizing without a whole lot of testing. It's not that the testing isn't possible (though it may be more difficult), but who wants to conduct an expensive wide-ranging double-blinded study when mainstream medicine won't accept it anyway? This was the case for many, many years. Even very recently osteopathic physicians weren't allowed practice rights in certain major hospitals; they stuck to their own osteopathic hospitals and no one questioned their modes of treatment.
Anyway, sorry; I didn't intend a history lesson. The point is that every legitimate science has external pressures that force accountability. When something doesn't have those pressures, as great as the ideas may be, weaker ideas slip in and become part of the canon. The pressure becomes internal--those who don't agree with the canon are on THEIR side, aren't loyal to the cause, etc.
I'm not being at all flippant when I say that osteopathy displays cultish elements. All the signs are there:
A revered, almost mystical leader figure (I know of one school in which AT Still's giant head is built out of bricks in the wall of a building built around two OTHER Still-related buildings),
Hostility towards outsiders and criticism (see the "diluting our schools" comment above),
Mystical overtones (one of my first OMM labs was less lab than New Age seance),
Preference of anecdote over documentation (See which is easier--finding detailed instructions for a laparoscopic nephrectomy online or detailed instructions on HVLA and craniosacral. OMM has a disturbing aversion to simple, replicable, widely-distributed algorithms. Cf. scientology.)
etc. etc.
So, long story short, I think OMM has great utility, and it has a bright future as it's only recently that osteopathy has begun to gain widespread respect and recognition. As its visibility increases, I think the science will get better and the days of technique-by-rumor-and-tradition will end. We're not there yet, though, by a long shot, and the only way to get there is to call a spade a spade. Tradition's great and all, but when it gets in the way of science it becomes at best a hindrance, at worst an embarrassment to the profession.