A couple of weeks ago a push-bot with mecanum wheels in “plus” configuration was able to beat two, arguably, the best robots in our state!
Seriously, in Final #2 three robots out of four overheated PTC and died, while plus-drive mecanum push-bot (3rd pick) was able to push three blue mobile goals into 5 point zone. This was the highlight of the competition. I wish I took a video of that game.
US Navy was one of the earliest users of mecanum wheels when it had omnidirectional forklift trucks that could maneuver in very tight spaces such as the deck of an aircraft carrier. In some places where they had to operate there was barely enough clearance just to drive, let alone enough space to turn around.
Unfortunately, unless one of the future games would have pathway or a maze with 20" clearance between the walls, it is very unlikely that benefits of the mecanum wheels could outweigh their disadvantages.
With mecanums for the ability to drive sideways at any given moment of time, just as easily as you drive forward, you have to pay with bulkiness and extra friction that requires more torque and limit your ability to gear up.
Onmidirectional X-drives have similar trade-offs but they take less space and are very good for the games when you need to turn on a spot.