In reply to matt pigden: you still get the same badge at the end of it. i think both courses are pretty much the same apart from if you go through ensa youll need very good french.
the french apparently require absolutely excellent skiing whereas the bmg do not require you (i think) to be such a god on skis.
with the bmg the focus on 50 "proper" scottish winter climbs seems to be a little silly given youll be guiding in the alps.
id say that british guides are pretty well regarded given there arent that many of them and when you look at some of the routes some of them get up and, more importantly, down theyre pretty bloody good.