I used a babbit bearing recently for professional stuff, part of the reason we didn't use a ball bearing was because of the size of the thing.
http://www.mcmaster.com/#6359k22/=10volie
that's the bearing we used!
On the last FRC bot I worked on, we used bronze sleeve bearings for the wheel shafts, which were running mecanums! Robot still runs perfect nearly 6 years later