> mv x y 2>&1 |fgrep -v "useless message"

An extra process just to discard a message of no possible use (warning you
that a file which no longer exists, and whose owner and group you cannot
now examine, didn't have the same owner and group as the new file).  What
an efficient, attractive solution.

Perhaps mv should output a line indicating each file it moves.  After all,
you could use fgrep to remove the undesired output.