I don't think it will matter. In years to come nobody will remember or care whether they met at 140 or 147 they'll just remember the fight and who won.

I've never heard anybody say Eubank had an advantage over Benn in their rematch because he'd been at supermiddleweight for longer than Benn, nor can I remember anyone saying Benn only beat McClellen because the G Man was just a blown up middleweight.