I have it on good authority that the reason some of the mustangs in Idaho are bigger and of higher quality is that some of the ranchers would (or still do) go out and shoot the stallions and put thier own higher quality stallions out with them. The same things happened in Oregon and Northern Nevada.
They are a lot of work. Generally way beyond what you would get with a youngster that was used to people already. How it worked when we were doing it, you'd get a ticket and that was the order you got to choose your horse first. My Grandpa was always pretty lucky and generally got his pick of the crop.
That said, sometimes getting them into the trailer was a bloomin' nightmare. Even with the extra large stock trailer we had. Getting them out was an equal nightmare. My Grandpa had a gift with horses though and we would train them and sell them to the Forest Service for pack and riding animals.
To the OP, I think your mistaken if you think you can't develop a connection with a just bought already broke horse. If you think you are going to get an immediate connection with a mustang, think twice. They seem to be harder to get their trust, but once you do, they'll do anything for you.
If you have no experience with mustangs I wouldn't adopt one without having spent time with people that know them. It's really asking for trouble.