I think a HUD is a great tool to have. It will help your win rate no matter how many tables your playing, the information is just to valuable.
That said, I believe that the ability to 1 or 2 table without it is invaluable. Learning to take notes, check hand histories while in play, and get reads like timing tells should be a prerequisite to using HUD. A player who can use these skills in conjunction with a HUD will be the most well rounded player and eventually be pwning the rest.