I would never use a rubber band or peep again. I love my no peep. It is great in low light situations and now I can shoot w/ both eyes open. I have an eye dominance thing and my peep blurred out on me. With the no peep, I picked up a few fps, and also I can see my entire target and shooting area quickly and clearly.
There are some drawbacks to the No Peep. It is tough to see the interior circles if you have a light or the sun behind you. You can also "make" the no peep line up even if you are not in your normal form. If you twist your wrist here or lower/raise your head there, you can make it line up. When you do that, usually your shot will be a little off. The no peep is not a total cure but overall I like it and will never go back.