I just discovered this keystroke and naturally the second thing I did after
trying it in an emacs lisp buffer was to try it in org. It didn't seem all
that useful, except with CLOSED lines and - lists, and so I'm wondering if a
slightly modified behavior might be better.

Consider a headline:
** TODO Something

Maybe M-m should go right before "TODO"?

Then again, with org-special-ctrl-a, M-m as it is now does provide a
shortcut to C-a C-a.

Just interested in what you guys think.

--Scott