As I know it, heavy, but head light racquets are the key to recovery.
Heavy racquets are better for the vibration transmitted to the body and head light to lessen the impact of the heft while swinging. I know head light heavy has made a world of difference in my recovery time.
According to this board:Fed=slap and should switch to a larger head frame. Nadal=god and only allows Fed to exists to fill his spot while injured.