Make them character bound, since I paid a premium price, i expect every one of my character get the special items upon creation. Say I try out a class I don't like and I already used my items, I want to be able to change servers, delete that character, and create a new one.
I want my founder pack items on that new character. I don't want to muck around with expensive(early game expensive) mailing fees and restrictions, I don't want to worry about bound weapon skins, I don't want to worry about ANYTHING.
I just want the exclusive items I paid for to show up on the new character and get into the game. Many other games have this working without any problems.