I would think, with my limited xc knowledge and watching the WC races only, that drop bars would work 90% of the time. I don't see much in those races that REQUIRE straight bars. Might offer a new perspective as well...

Also, at least from what I have seen, old xc races where drop bars were used, were more technical than todays standard xc race. Again only from what I have seen on tv or movies.

I doubt many people would argue using drop bars on a dh race of todays standards. Even Tomac said he thought it was insane to run drops on his dh races. In dh you really are much better off up and back. Not down and forward. You could ride dh on drops, I just doubt you would have the speed or control