[MrForbes]

Nice!

The bump problem is probably due to the interesting things that happen with 8wd and the center of mass of the robot, and the angles at which the forces work when the bot is at a 45 degree angle.

I suggest you draw a free body diagram of the robot in the position where it gets stuck, and figure out the tractive force on each pair of wheels, and compare it to what is needed to get over the bump. Might be that adding some weight at one end of the robot, down low, will fix the problem.