I think things must be very different where ever you live than they are here.
Most of our barefoot trimmers are extremely well trained and have certainly not just done two week course in hoof trimming!!! In comparison we have a few of farriers who shoe over here (supposedly very well trained as a farrier) who are not properly trained as far as barefoot trimming goes and think going barefoot is simply removing the shoes. Years of training does not necessarily make someone an expert - things change.
You are lucky to have a farrier who truly understand the physiology of the horse.
I would also not call the mustang roll, crap nor low heels - which are actually, if you take a look at wild horse hooves, the norm.
I do agree however that one size does not fit all as far as a trim goes and it depends on a lot of things including conformation, amount and type of work and working surface.