I'm surprised no one has mentioned prostate stimulation and pegging yet in this thread. I am convinced that the orgasm you get from pegging is as close as a man can get to experiencing a female orgasm. It has many of the same characteristics - much longer, a whole body sensation rather than localised and certainly has the potential for multiple orgasms when it is non-ejaculatory (which it sometimes is).
It is also not a sure-fire thing. Sometimes it just doesn't happen.
I don't even know if the orgasms I experience from rectal stimulation have much to do with the prostate. What seems to happen is that at a critical point the pc muscles go into involuntary spasms and I experience immense waves of orgasmic pleasure. I have experienced up to 9 of these orgasms in one night, but the usual score is two or three.
I think these orgasms are analogous to that orgasms women experience but I have no real way of knowing.
And yes I would love to have the chance to experience having a woman's body. Not just for sex but to be able to interact socially and be accepted as a woman. What a weight off my shoulders that would be!
What you say matches my own experience. There is no doubt that despite all efforts to relax the pc muscles just start to do their own thing. Of course their tensing causes the stimulation to become more intense and, although the orgasm builds far more gradually than a normal orgasm , this is very much the point of no return when you know there is nothing you can do to stop it (even if you wanted to).
My wife describes her own orgasm as a wave over her whole body and it's this commonality that makes me think we are experiencing, as much as is possible, the same kind of orgasm.
BTW I first experienced this type of orgasm while climbing a rope in the school gymnasium (I damn nearly fell off!) and I have read about others experiencing it in the same way. It was the memory of this experience that made me realise what what being on the receiving end of a strapon would have going for it (and many thanks to Channel 5 for showing a 'demo' that gave me the opportunity to ask my wife).