I think he would have actually won less slams. Part of what makes Roger so deadly is his flexibility and trick shots when put in a difficult situation, for example, when he employs his wrist flick single handed backhand passing shot while forced deep in the corner, and opponent being at the net.
Secondly the transition between one handed slice and one handed top spin backhand becomes much more fluid with a 1HBH, and it comes very natural to Federer. The 1HBH perfectly suits his game.
3x Prokennex Ionic Ki 5 , strung w/Wilson NXT 16 @ 60lbs
NTRP 4.5 lefty