I am usually working with fifty to hundred open files at the same time in Emacs. Not more, at least on a regular basis.
I experienced crash (Windows only) from time to time (one per month ?) but my feeling was that they were related to `flymake-mode' (I use it for CSS, Python and Javascript) in relation with `semantic'. Never thought it was related to `global-revert-mode'.
I have read that the time stamp check was aborted when the user actually use Emacs and the documentation of autorevert.el says: "You should never even notice that this package is active". My experience and feeling is that the documentation is right.