I have a Shoei head. I took a Shoei DS in Jan when we chased Dakar. So did my riding partner. Worked well, dust wasnt as problematic as I'd figured, vented very well - use a SixSixOne Fenix and M2R Rev 3 (since the Fenix vents like crap) - was worried the Shoei would be to hot. Easy enough to flip the visor and use Oakley O frames (fit best) when necessary. Help vent even better.
We both felt it was the best of both worlds. Its held up very well
ATM you can find them being discounted as Snell 2010 is coming in. Local shop has them for sub $350.
Otherwise I have heard people recommend the Airoh Tyger
Now replaced by the S4
or the AFX FX-37 (now FX37-DS new for 2010).
Friends have the AFX - I've handled the Tyger. They meet good standards, but they arent as durable, quiet, comfortable, vent as well or are as well made. The shields optical clarity suck - distortion was readily apparent. Friend has had issues with the AFX liners and trim. But they both are about a third what the Shoei costs.