Vance, I don't understand why you think our climate is not good for Japanese black pine. I know a lot of people who grow them in northern climates with no problems as long as you protect them in winter, and be careful with the heat of mid-summer. Same goes for Japanese white pine.
There are also some very nice black pine being field grown here in the U.S. for bonsai. There is good stock becoming available, but I don't see that for mugho pine, just plain nursery stock.
Will, your gallery doesnt convince me that black pines are inferior to other pine species. You don't seem to have a lot of good examples of black pine pictured. I think that in terms of yamadori, mugho and black pine are on a par. In terms of field grown stock in the U.S., black pine are superior to mugho.
I don't think that growth characteristics of mugho are any better than Japanese black pine as far as back budding and needle reduction.
Just my opinion.