It Really is the Right Stuff.
I have the MC-34 and MH-02 Pro, which I use with my 600 II and other lenses. I prefer the screw clamp to the lever clamp for the monopod head, as I'm often carrying the 600 II over my shoulder on the monopod, and a lever clamp could catch on a pack strap (I have their lever clamps on ballheads and my gimbal, and they are great there).
If you only plan to use the monopod head with the 600 II (or other collared lenses), save a little weight and $, and get the MH-01 head. The difference is the MH-02 can be rotated 90-degrees (to attach a camera body plate) with a screw knob, meaning you can swap back and forth in the field (the MH-01 with the right clamp can be rotated, but you need a hex key).