[MattC9]

So, there are a few more questions you need to ask you're self like, Do we want to go over the bump, ramp ect.? If yes go with the 8in AM plaction wheels (they give you a lot more grip) which are good for going on the ramps and getting grip over the bump.

Also it sounds like you have a long drive base so use omni's in the front, a 4WD is like a mullet "omni's in the front, plaction in the back" or vise versa, it's all about how you want the turn. Also pleas use the dual omis they tend to "bump" around less (you want to eliminate the space inbetween the rollers on the wheels).