The best benefit that Live has is its system wide connectivity. E.g. I can see in my friends list who is doing what all the time. If they're in multiplayer, I can see which map. If the session is not full I can join them in a single button press. PSN has nothing like this - it's the games themselves that have to implement it. I think there's only a handful that support joining and even less that tell you exactly what a friend is doing in game.