HUD is a tool. Look at it like a chain saw. If you know what you are doing, you will probably be at least as good as other lumberjacks who also have them. You will probably be better than other lumberjacks who dont have one. If you dont know how to use it correctly, however, you will probably lose limbs.
If you play <6 tables, and can pay attention, you may not need one. But, if you know how to use it, it will NOT hurt your game. It also may not help it.
Its a tool, and must be used correctly.