You know you spot a good suggestion when your head starts flowing with ideas for new mechanics, minigames and maps as you read it. It's just awesome, and it feels like a good job with balancing was done here.
I think that the direction boomerang goes in returning trip should not depend on player's settings, because in a pvp situation environment can change quickly when chasing a player. Instead it should check whether player thrown it is using main hand or off hand. This way you could easily decide to throw it on the side where it will have more space to return.