It is interesting
No doubt slower surfaces has helped him against a big server like roddick, but nadal started challenging him outside clay from 2006 onwards - right in the middle of his prime years
Say if federer lost 2 wimbledons and us opens to roddick/another big server, he would've also gained a similar number of slams from nadal from 2008 onwards. In fact, I think the slower surfaces have benefited nadal against him, more than it has for him against roddick. We've seen federer can play short point serve and volley very well in his performances against sampras in 2001, and then his wimbledon victory in 2003 (when S+V was still a big part of the game) in which he defeated roddick in straight sets at the semi-final.
His serve is probably better than roddick as seen in the 2009 wimbledon final, roddick served out of his skin but still got out-aced. So I have no doubt that he'll still flourish in very quick 90s conditions. Nadal on the other hand, I'm not sure about. His serve is still pretty shit considering he's won 11 grand slams with it, his volleying and general net game is even worse.
No doubt that nadal was more beneficited , especially on grass.......
in 2007 , The wimbledon`s organizers decided change the natural grass for rolls of grass because the natural grass aren`t good because the courts were not capable to recovery fast and they thinking in the olympics game this year , that change of the natural grass to the rolls of grass transform the grass in a more slow surface and with much more high bouncing and just that year was when nadal started to complicated federer on grass.
that rolls of grass destroyed wimbledon and the form of cut the grass too + heavy and big balls kill this tourny in all aspects , the change the grass , they cut the grass different to stop more the shots and use more heavy balls