[Daru]

We intend to use 6 omniwheels, 4 of them oriented in the forward-backward direction, and two of them in the left-right direction to allow side to side translational movement.

To use only 4 motors, we would need to link the forward-backward wheels with chain, like you suggested. I fear that using one motor on each side of the robot would severly limit what pushing power we would have.

Two two CIM-like motors would be for the side-to-side translational movement (and maybe turning), which we don't intend to use to push with, so lacking power there would be acceptable. We would like it to be close to the same speed, however it's not too important as long as it moves us fairly quickly.