"If he likes the current size, why should he change?"
True, why should he change if he likes it....BUT, he's asking our opinion.
I have been a CWB team Faction rider since late 2003 (who cares tho). I have been on all their boards and know them pretty well. "My opinion", he would ride the 140 better with his weight class. Tonis is right on with what he said. My thoughts are the same.
Try both tho, everyone has their own style. He might actually like the bigger board for comfort.