Nah they can remember stuff overwritten on them by kids coming to the board - although that seems to be a dying thing. I also still like to stand by a board and be able to interact with it rather than sitting at a pad or visualiser

Wireless graphics tablet. Stand wherever you want, not just by the board. Kids can write too, even from their desks. You could get a fancy one that mirrors the computer screen and it'd still be less expensive than an interactive board.