Chain driven vs Direct drive mechanum

[Tom Line]

Pro's of Direct Drive
1. Less components
2. Lighter Weight
3. No chain tensioners to worry about

Con's
1. If you don't know the exact drive ratio you want for the bot, it's harder to adjust speeds with direct drive.
2. You're locked in to putting your transmissions at the 4 corners of the robot. (This year that would have been bad - you would have really limited your space for the ball and your kicker.
3. Servicing can be difficult if you aren't carefull with the design with direct drive.

In your case, if this is a learning situation, I'd definitely say go with chain driven so you can play with your drive ratios until you're happy.