it's a common MTF misconception to think that the court's speed is a very important factor for federer. it isn't. what matters the most to him is the bounce's hight.
federer can play at or near his best in a low bouncing and slow court. hence he has succeded in the WTF (slow and low bouncing hardcourt) and in hamburg (slow and low bouncing claycourt). even grass the changes can be seen. when the grass was lower, federer was better. his forehand worked better and his backhand worked a LOT better.
yes the bounce is very important, but more than the court it's the balls as well I think (better not heavy balls for him).
Recently I've often read the players speaking about the balls rather than about the courts.
And the weather which can change much the conditions when it's played outside (when he played against Nadal in Melbourne it was a cold day, and humidity can change the conditions much as well ; in Wimbledon the bounce is lower in second week when it's a rainy fortnight like in 2001 or 2007 rather than after a dry weather like in 2009).
And of course it depends who the opponent is.