I guess the first thing to think about is how much money and time do you want to invest in this concept? The second thing to think about is how easy or difficult would it be to implement and operate. Chalkboards and whiteboards have the characteristics of being inexpensive and easy to use. You might also consider that you can buy an LCD TV/monitor and a computer off the shelf that could be used for the project, which would be very flexible for advertising establishment specials, league scores, events, etc...