When you say that IP / IS is only a body, physical thing you do realize that you are getting your feet into a Cartesian mudpool ? Modern top-athletes are moving away from this kind of thinking. And so are surgeons and biologists. The human body is not a machine. You cannot separate the body from the mind / spirit. Science has moved on since Descartes.
tom, may i direct you to this thread http://www.aikiweb.com/forums/showthread.php?t=21943
please read through the posts then we can continue to discuss. btw, i had my hands on Saotome sensei and took ukemi. i had more frame of reference than you think. other folks, proponents of IP/IS, have similar experiences with various high level (as in Ueshiba Sr uchideshi) aikido teachers and other martial arts. their combined experiences are staggering. as i said before, when a bunch of very experienced folks said the same thing, there might be some truth in it, at least one should pause and ponder.