I'm just now getting to the point of using this in my ongoing campaign, but for story reasons I need to shift it to magic users riding dinosaurs instead of cowboys, but this supplement is a big help.
One thought I've had related to the speed of mounts is that for simplicity the first maneuver that is taken by a mount they move the equivalent number of moves equal to their speed. So as you have it if a rider spends a maneuver to let a Speed 2 mount move it would normally get to move 2 maneuvers worth. I propose that it should move the equivalent of 3 maneuvers (2 for the first maneuver plus 1 for the second maneuver). This is much easier to use in personal scale combat and is easy to track and show how faster mounts really make a difference.
Just a though. Thanks again for providing this!