In my experience (Dalton walnut calf and BB 5th Ave walnut calf) I haven't been able to notice any flaws that anyone on the street would see. Unless I get a really good deal on firsts I will always look to seconds. If you're totally anal, go with firsts.
Toronto members - FYI, Robert Jones in Royal Bank Plaza is liquidating their AE stock. Everything they have is 50% off. Their regular price is $365 on most styles. They have a lot of styles but not much in the way of sizes. I picked up some 5th Street in brown.
I also found out that they now sell Saphir products.