Wow, I wrote my post because I had only read this thread until page 30 or so and I didn't see that Start the Game covered all the points that I had about Federer's game, sure in a more inflammatory Rafa fan way, but overall he is right about Federer style, which can't be considered really aggressive from 90s or early 00.
If you played Sampras, Edberg, Becker in anything remotely fast in a good day for them you would barely be able to see the color of the ball, as it would have past you by most of the time. With Federer, even in the fastest of conditions it wouldn't be the case, as he likes to rally, let you in points and gain a certain rhythm.
Sure he can be devastating, consistent, versatile with the right touch of aggression like he did with Hewitt in the US open of 2004. But guys like Goran, Becker's on a hot day you would barely be able to touch the ball. That's the difference in aggression in faster conditions.
You know Federer was 5-0 against Sampras, Federer and Krajicek on very fast carpet/grasscourts when he was only 19-20 playing them when they were 29-30?
Federer handling Ivanisevic's serve:
Federer breaking Krajicek:
Federer never had a problem with big serves, in fact I think he hates returning Nadal's serve much more on grass, so much spin he cant counter the pace back at Nadal.