I was speaking to CF today. If I talk to him again this week I'll ask the question! When I ordered my Premier Cru I specified a lightweight bat, so rather than expecting a monstrous bat I did say to him I'd prefer thin edges and a bigger swell if he needed to lose some weight from somewhere.
I consequently got a rounded bat face, so I think that because he knew I wasn't hung up in edges he didn't use the flatter roller.
That said, my Laver was my first flat faced bat, and after getting used to it I loved it! I think it feels like you're presenting a bigger surface to the ball and actually makes the bat feel wider (weird I know)