[SpeedFreed]

It is true that basically this only improves the strafing abilities and adds symmetry. While I can imagine it must have some effect on top forward speed, exactly how much is a question that can only be answered in testing. Also, speed can always we compensated for, like my teams new octanum--powered by 6.66 CIMs and does 22fps on mecanum (after mecanum loss). Likewise if you power each corner of this with 1 CIM and 1 Mini CIM, forward loss will probably be quickly forgotten.

As for 4 omni wheels, I'm not quite sure what you are getting at. If you mean replace one set of mecanum wheels with omni wheels, then you would need at least 6 independent gearboxes to drive all the wheels (4 for mecanum, 2 for omni wheels) (or differentials, but THAT truly gets in the realm of unnecessary complexity), and then that is some strange mix of H drive that really holds no advantage. If you mean just 4 omni wheels, then that would have to be holnomic drive, which only reaches top speeds on the diagonals (unless you do 4 omnis Killer Bees style, and then you have to be magic to drive it).

The biggest pro's I was getting at with this, is that it provides full motor power in the cardinal directions (unlike H drive), and is symmetrical like swerve. But it is also heavier, more expensive, and harder to make than mecanum, for probably not enough gain.

However if your team does mecanum every year without exception, and is tired of it's asymmetric performance, then this is the drivetrain for you!