Well, I shoot a lot of polo with the 400 f2.8, and move around the edge of the field a fair amount when I can. I have been using a Velbon Neopad 7 CF tripod with a RRS lever release plate affixed to the top. This has been working very well for number of years, and I liked the single twist on the Velbon legs versus the older Gitzo. However, I am about ready to get a new monopod, as the "stops" on the Velbon sections keep breaking out after lots of heavy use collapsing and extending. Most likely, the replacement will be the big Gitzo in the new CF and with those new locks. The Velbon, has been a very good value, but it is just getting worn out at this point. I like the design and easy deployment. It is solid to work on, pivot, turn, etc., but the stop in the ferrules seem a bit weak in design and start to come out. Field repair is easy, but should not be needed, IMHO, so it will be replaced for the fall shooting season.
The RRS clamp makes a world of difference in allowing you to break things down or set up quickly. I use the lever release, which RRS does not recommend, over the screw type QR. I sent my LR plate back to RRS to have them tighten the cam to make sure the LR would not slip. That has worked perfectly. There is no need for a swivel tilt thing with a monopod, as that is really controlled with height and spinning about the pod, and alleviates the one more device that can mess up part ;-) If you need to do a lot of tilt and swivel type stuff with a heavy lens like the 400 and up, a gimbal head on a tripod is a much better solution.
One other thing....the neckstrap attached to the lens really has saved me, and now becomes a method for shooting. I let the camera and lens swing away from me while keeping the pivot point secure on the ground, and that lets me bring up a second camera with a 70-200 attached for close in shooting. Never have to put a rig down, and never miss fast approaching action.
LJ