it does work, and thats my main concern, would the next copy be better or worse optically? I haven't been able to really tell as all my shooting with the lens has been inside the house with my "noisy" 7D. But nothing is blurry or shout out loud sharp. Just me i guess.
To return one for another, then return that for the first one would be imbarrasing.
"Bad copies" with Canon L is IMO mostly urban legend.
What is certain is that chipped or worn paint greatly reduces the used value of a lens. This is because it usually indicates a *lot* of use or maybe abuse, and it's otherwise hard to tell that about a lens.
What we haven't seen is whether this is an actual chip or some tiny surface flaw in the paint that's normal.