I have no direct experience with V-O frame sets, so I can't attest to their goodness or ride quality, but having converted a few 70s and 80s road bikes to 650B, one big advantage I can see with the Polyvalent is that you don't need to make compromises: You can use canti brakes so no need to search for long-reach calipers; since it's built for 650B, you don't have to fiddle or worry about fender line; the long top tube is intended to compensate for the use of upright city bars, plus as others have pointed out, it has loads of brazeons for fenders, racks, etc. I'd guess that a lot of them will be sold as complete bikes built by V-O dealers, rather than as frame sets. You can go to the bike shop and walk away with a complete 650B city bike for about a grand. If you're in the market for such a thing, that seems like a pretty good deal.

Neal