The way xp is shared in a group setting has to be revamped. You should not get more XP duo or solo than a full group. I know it makes sense the way it is right now, but it simply isn't healthy for an MMO. I 2box mostly because I am forced to for maximum grinding, even ducking friends and guildmates on a double xp weekend. Am I selfish? Probably. But everyone in Norrath is there to maximize their gameplay.
Simply put, the xp rules should be modified to give at LEAST the same xp as if you solo'd a mob, if not more. It is a multiplayer universe, we should be encouraged to treat it as such.S