I think the rubber band is a bad idea. Players can't wear them, why should the official. I can imagine the following conversation;
Official: "Hey, number 22, you need to take off the rubber band."
No. 22: "But you have one on your wrist. Whats the difference?'
Official: "I have to wear one because I can't remember who has the next possession when there is a jump ball."
No. 22: "Isn't that what the goofy looking arrow is for on the table."
Official: "Yes, but they may forget to change it."
No. 22: "But if you're too dense to remember who has the next possession what makes you think your gonna remember to change the rubber band to the other wrist?"
Official: "Tweet!, Technical foul on 22 white for being brutally honest!"
Seriously. I am working on getting better at keeping the arrow in my head. It is easier at the JV and Varsity level than when I call JH and young kids in Rec. ball. If you must use something, I think an extra whistle or roll of mints in your pocket is better. It avoids the above conversation and you can discretely move it to the other pocket when you get to your next position or while the player is moving to the throw in location.