They work. They have little scratches, not fatal flaws. Its like going to a factory outlet store and buying a t-shirt with a messed up print on it...a mess up when they were silk screening the design. Nothing more.
What you have to remember is that a bak-pak has no moving parts other than the pump. The pump is made by Rio, not CPR, so regardless of getting a 'premium' bak-pak or a factory second, the pump's always right off the shelf, and isn't covered under the CPR warranty anyways.
I checked mine out thoroughly last night, and except for a couple very light, very minor scuff marks, I don't see any other blemishes. I fired it up last night (took a whole 3 mins to setup) and this morning I had about 1/3 cup of skimmate. It's also a little quieter than my Prizm was.