[daltore]

I think it would be a little simpler to program mechanum reliably as apposed to omni, as with mechanum, you can have a regular tank drive operator interface with one of the controllers also controlling side-to-side motion on the x-axis of the joystick. This is fairly simple code, the hardest part is just telling the processor how to move the front wheels back and forth opposite the back wheels, but that's pretty easy. With omni holonomic/Kiwi/Killough the robot pretty much has to be programmed to know what's forward. From what I've seen in VEX, Mindstorms, and FRC, mechanum tends to lend itself to a slightly more powerful drive train, as omni holonomic has almost no resistance to movement, basically making it a hockey puck on wheels (note the incessant fishtailing of 2158's robot from 2007 FRC, where we only had 2 omniwheels, and were pushed around easily).