Just thought I'd post a quick update, since it's been so long.
Monty has gone from a horse that would violently rip the lead out of your hands, to a horse I can lead around with just a hand under his chin.
He has gone from a horse that would run to the farthest end of the pasture and puff and blow at any stranger, to a horse that has found it is well worth his time to be first in line to greet any new stranger. (Because people are cookie bearers!)
First couple times I trimmed his horribly overgrown feet, it was in the air while he was continually rearing. Now he stands to have his feet done like a pro, his feet are perfect, 100% sound, and I can trim him all the way around in about 20 minutes.
He used to flinch at any touch - a stroke, a brush, didn't matter what it was, he didn't like it. Now I can touch him anywhere, pat him firmly, walk behind him, exclaim and shove him on his rear and he just stares at me like "dude, why are you so weird."
The day Monty arrived:
A now, a bit over 1 year later: