John,
The Sirui VH-10 became available here in early winter this year, so they are very new still. Their one drawback has been the stiffening of the horizontal viscous movement in sub -10 centigrade temperatures. Although my unit still works at -20, with smooth panning, trying to move the head quickly in the horizontal direction is impossible, and one or two buyers have broken theirs, presumably because they tried to force the movement when the fluid had stiffened. The importer has told us that Sirui is changing the viscous fluid they use to rectify this, but I haven't seen any of the "upgraded" units yet. Once they come, I'll try them and if the movement in normal temperatures is still as good as now, I'll swap again. I'll keep you posted on these forums.
In general, the VH-10 is really well thought out, and super stable. One aspect I especially like is the rounded shoulders of the top platform, which give much more space for the focusing hand with collar-type focusers such as Nikon and Swaro scopes have. The quick-release plate is also very well thought-out, with a machined beveling in the head that greatly facilitates pushing the plate into its place. The telescopic handle is also very good and allows much more flexibility in handle orientation than any of the Gitzo or Manfrotto systems I have used.
Kimmo