Hello, I'm from 3641, we did a different kind of H-Drive. Our system was called a deca drive, this consists of 2 CIMs driving a center gear in the middle of a seesaw type system with two small omni wheels on the ends, connected by gears to the center gear being driven by the CIMs. When power is applied either way, the system throws that side down into the ground (just from the motor's torque) and spins the omni wheel at the same time. If we switch the direction of the motors, the seesaw simply tilts to the other side. When the system is not being used, the seesaw balances even with the bottom of our robot, allowing us to easily go over the scoring platforms. This deca drive worked very well for us in Recycle Rush, and thanks to our four main drive wheels being omnis as well, we were very maneuverable.
Pictures of ours are attached, and a video of robowranglers with a similar system is right here:
https://youtu.be/oRwvQ2D_B-c?t=34s