[Stephen of REX]

Your links aren't working for whatever reason, so I'll just tell you what I know about mecanums. 16:1 on 8" mecanums is very well balanced setup.

As for mounting the wheels directly on the toughboxes, I'd strongly recommend against it. A better bet would be to mount the wheels on the chassis, and have them chain driven to the toughboxes which are situated on top of the chassis.

Another alternative to toughboxes is Banebots transmissions, they're what we always use.