Going back to the barrel floating I have had a similar experience and findings to Cloverleaf. I floated my HW100 with a Rowan cylinder band, and quickly put the original barrel band back on!
The cylinder on the HW flexes where it goes into the action giving all sorts of problems of moving, flexing and rocking as mentioned. It would seem that the HW band supports the cylinder by hanging from the strong barrel, not the other way around like most guns.
With a Rowan band fitted and the barrel floated, I could squeeze the cylinder and barrel together far too easily for my liking. If I was you I would just try using a slimmer o ring if you are concerned about zero shift, and leave the original band on.
It is not a case of some people for or against floating like wobblybootie states, but whether the design of the gun might benefit from it. My Ev2 floats without a fixing to the cylinder with no problems, but I dont think that the design of the HW lends itself as well to floating. Some seem to float them ok but others like me are not convinced.