The M3 is more compact than the M4, and
more appealing to the good and better players.

The M3 will launch the ball easily
(courtesy of a tungsten weight in the sole)
but the ball flight will not be as high as the M4.

If you strike down through the ball with
good swing speed, then the M3 will probably
give you the distance and forgiveness you
need with a little more control.