I don't disbelieve you -- and, in fact, would report the same. Model Ms are awesome.
What makes a good keyboard is very much a personal thing. It depends on many factors. How tall you are; what position you sit in; what kind of chair you use; how high your chair is adjusted; what your posture is like within that chair; how high your desk is; how high your desk is relative to your chair; how the monitor is oriented; how long your arms are; the ambient temperature; how large your hands are; how strong your fingers are; what position you hold your fingers in over the keyboard (I maintain that holding your fingers over the home row as a default position is insane); how often you take breaks; what kind of exercises you do during those breaks, if any; what kind of exercises you do before sitting down to type, and when you're done for the day; and how many hours a day you type are the first few factors that spring to mind. I didn't have to try hard to come up with this list.
So the Model M works for you, and it works for me too. Lucky for us, because they truly are sweet keyboards (...till you try to hook one up to a mac). But that doesn't mean they'll work just as well for everyone else.
(The same goes for pointing devices, too.)