Yes Andy Murray is superior on grass because he won 7 Wimbledon titles. And Fed played all his finals indoors . Good thinking !!!
Superior on grass comparing with Novak which is fact and 1 Wimby title for Novak doesn´t make difference, when Andy has 3 Queens, Wimby F, OG gold and so on - clearly he is better grass-courter than Nole
About Roger - their SF match might be tough one i think Andy is going to be favorit outdoors and indoors it is more even match