I know exactly what you mean Jim, and that's why I thought the edges would be hard to smooth against multiple colors at once (even if they were transparent) and still look good.
I just finished making Christmas cards with our Chinchilla on them, the only good picture I had of her was taken while she was in her cage against a black background and you could see the cage bars through the hair on her tail. I had to clip her out of that and then stick her on top of a white background for the card (did I mention she's black with a white belly?), it turned out great but took multiple hours, I even added a cute Santa hat.