"McBains a dog"? - well, I am afraid I will have to disagree with WeThreeKings's assessment.
In my opinion, McBain will improve his starting skating and his overall stride while at BC next year, which is really the one main knock against him. He is almost 6'4", has quick hands, a seriously extended reach, and once he's up and running has no issues skating with the competition. Looked fine at the U18s, but for some reason was playing on the wing, which is not his natural position, so maybe teams see him as being more the protypical power winger.
Not a first pick for Les Habs (go for D) but he may go late first early second to another team before Montreal has the option to decide.