Wow, that looks truly monstrous!!!

I'm seeing notes on the web indicating that the TS-4.2 has a welded base, while the TS-4 does not.

Otherwise it sounds like a bunch of minor updates.

I think the TS-2.2 is designed to accommodate most 29er wheels with tires mounted. The TS-2 would require the 29er tires to be removed.

The TS-4 series appears to be more oriented towards fat wheels/tires, but of course, would be multi-purpose.