Pros/Cons of Various Drive systems

[pintsize131]

I was wondering if anyone could help me come up with pro and con lists for a couple different drive systems for this years (2011) game. Or, offer up a different drive system entirely. My team is wavering between Mecanum, Omni, and Tank (with a few different combinations of wheels: all traction, all trick, or half and half). If you have any suggestions, that'd be great. Thanks for your help.