I've been the happy owner of a Desmo for over a year now and it has surpassed expectations. It's much better than any other helmet I've tried at handling turbulence in a straight-line and especially when you turn your head (it barely registers side winds at all). It's as quiet as most closed faced helmets but can also be opened up when not travelling at high speed. The visor lets you go from open face to jet to fully closed a second, one handed.
Roof has updated the Desmo to the RO32 Desmo with a variety of updates and improvements. If I can find a retailer I'm in for the upgrade.