You guys shouldn't worry so much about the speed of the HC. Fed will always have problems on clay especially against Nadal. Nadal's game and foot work are tailor made for clay and he is simply better than Fed on that surface. Fed's footwork will be a lot better on HC and he will be able to defend his forehand side easily even on a slow surface.
After watching the FO final again, I can say with confidence that he will have less trouble with Nadal's heavy topspin to his backhand. He has definitely made that side a lot more stable. He doesn't have to go for a winner from that side. He just need to hit it deep consistently and he was able to do so during the FO final.
I fully totally completely agree. That's why I'm more confident going into the grass and hc season than the previous years, actually very confident, if he is fit, because the alleged weaker side has been looking so good.