From what I've seen the benefits of having Mechanum wheels are:
- Allows for good freedom of movement
- Amazingly agile
- They look cool
I don't know how they are for speed or if having them effects that at all. However I have seen my teams robot push mechanum wheeled robots almost anywhere. There doesn't seem to be anything you can do once we come up behind you, if we wanted you to go away from the rack then thats exactly where you were going.