Hi, People say Federer is the only player using gut in the mains, while all other players that use gut put them in the crosses. I never understood that Federer idea, once at first sight mains should be tougher string, so not gut. Now some stringers information seem to show more and more players are using gut in mains. Anyone has an idea if this is true?! And also what's the advantages/disadvantages of either option? Thanks.