Yeah and likely the biggest difficulty is dealing with resorts that have real dh tracks on them. They are above and beyond most double blacks in whistler for example.

Definately. When you look at garbonzo it is 30 to 40minutes for an average rider to descend. Steep, technical, drops, jumps, steep (I said that already). Its a double black because it is sooooo long. Its tough to come up with a standard system. In my world that track in michigan can't be double black, intermediates can't ride double blacks, they walk 40% of it.

I think, if this was to work, you would have to work from the lowest common denominator (rail to trail for example) and the hardest (north shore, platekill, cali dh racing) and then work inwards.