I agree, color has little to do with the genetics behind egg productivity. It could be argued that Buff orps (at least large fowl) are "better" egg layers than other colors, simply because that is just about the only color offered by hatcheries and hatcheries breed with a heavy emphasis on egg production (and little attention to anything else like meat production in DP breeds or conformation to a standard) and there are a lot more hatchery buffs out there running around in urban and suburban backyards than any color of exhibition orp. But in that case, it's not so much that buff colored birds are better egg layers but that it is the only color hatcheries who focus mainly on egg production. If hatcheries sold just as many blue/black/splash, lavender, or other colored orpingtons, then you would expect to see the same kind of egg production in those colors. Also, while hatchery birds are often more prolific layers during the first few years, they tend to burn out faster and as they age their rate of lay drops off more sharply than non-hatchery birds who will lay fewer eggs per week than a production bird but will lay the same number of eggs for more years. If that makes any sense.
Speaking of egg laying orpingtons, I am wondering if my big blue girl might be getting ready to lay. I checked for eggs tonight (nothing for the last 2 weeks almost, one of my 2 egg layers is in quarantine in the house and stopped laying due to stress and the other girl I had laying has either stopped also or is incredibly good at hiding her eggs from me) and one of the nest boxes about looked like it had exploded! The 4 older girls would rearrange the hay in the nest boxes from time to time, but they never fashioned such a deep nest. Of the two new, just about POL, pullets I have, it seems the tiny Ameraucana would be less likely to dig such a hole for a nest. Maybe I'm wrong...but here's hoping for a pretty brown pullet egg sometime in the next week or two!