[Jared Russell]

We used a holonomic omniwheel based drive in both 2007 and 2008, and I cannot foresee us doing it again unless defense is explicitly forbidden ala 2008 (even though we managed to win a regional in both of those years). Simply put, the gain in mobility did not offset the loss in traction. Determined defense from a skid steer bot can still shut you down.

As far as omni vs mechanum, the dynamics are identical. The only benefits of mechanum are that it is often easier to mount the wheels and motors parallel to the frame. Also, it is somewhat easier to make/buy mechanum wheels with larger floor contact patches and better tread material (though I have seen omniwheel with roughtop tread rollers before).

I should also emphasize that using omni/mechanum drives effectively is still a large challenge. Wheel speed must be closely controlled, a suspension is highly desirable, and weight must be distributed carefully.