With the ramps under it it's ok but without them the drop is too high and our gearboxes fell off. Also I don't know how long the soft rubber tires will not be completely chewed up.
We don't see the advantage of mecanum wheels considering the barrier. Even with the upside-down ramps (which would be tricky anyways because of the bumpers), the jolt of going over the barrier in such an ungainly might be too much for the robot.