As a general rule, its better to be lefthanded in tennis. As a lefty kid, you grow up playing a lot of right handers, whereas right handers don't have as much experience going up against lefties. There are also service benefits.
Federer would have been scary if he had been a lefty.
exactly. fed would not have his losing record vs nadal, and moreso, fed would have dominated even more so. 20+ slams are not out of reach for him.