Hey Dayne!
My mustang does just fine with my domesticated donkey and arab and draft. He's not BLM, but was foaled on a feedlot in Nevada. His dam was a wild estray, from what information I could gather, who shipped for meat.
My mustang was saved by a wonderful bunch of women I can't locate to thank. Together, they saved six or seven feedlot foals and then sent them to different rescues in surrounding states.
However, : ) I have also heard of BLMers having a hard time mixing with domesticated horses, but my take on that is, I think the wild horses often have trouble with *everything* after capture. The older the horse, the harder it is to adjust.
My mustang is hair-trigger hot, but he's also exceptionally gentle. Last summer, my 16 year old, sight-impaired terrier snuck outside and wandered into the corral where my mustang was running and playing. Unable to stop in time, my mustang *jumped* the dog as if he were a jumper, (never saw him jump, before or since), throwing me a look as he flashed past. I was amazed.
He knew -- he absolutely knew what he did. It could have been a horrible accident; I was so grateful that day for his mustang heart.
I knew a BLM mustang, four years old, bigger than mustangs, usually, at almost 16 hh that was completely (mortally) out of control. It is the only horse to date that seriously scared me. I couldn't even walk beside the horse, and the trainer had guts, imo. The horse was one angry boy about the whole BLM capture; he constantly bit people, and you could see in his eyes that he was enraged. He blamed ALL humans. I doubt he was ever gentled.
On the other hand, one of our neighbors has two wonderful, gentled BLM mustangs. He rides horses for a living, working a ranch, and his mustangs are wonderful, and well-trained by him. Sometimes it's more the human that's the problem -- there are people who adopt these horses as a novelty, without being fully aware of what this kind of adoption entails. You surely better know what you're doing.
So, mustang-wise, it could go either way. I *love* the idea of the Colorado Prison training program tie-in. It's a godsend, to both the horses and the prisoners.
Em