Agassi? Ha... Federer ripped Agassi with his backhand in so many ways it's unbelievable, he won the US Open 2005 match against Agassi (when it was windy) because of his BH.
First of all, their wind match was in 2004, in the quarters, which Fed barely won in 5 sets.
Either way, you're trying to compare a peak Federer with a 34-35 year old Agassi? You're making his point for him.
Federer's backhand is great at passing shots, but as Clydey said, its a borderline liability in baseline exchanges.