Until someone can give evidence that the balls in fact weigh differently and are made differently, then there is nothing to go by. There is however, multiple videos and testing done to prove the balls are similar in weight, albeit they are off by miniscule amounts.
http://www.youtube.com/watch?v=RbHACd8yymY
http://www.youtube.com/watch?v=p8sjRqLFwAw
Both balls weigh 5.9oz, if someone so happened to have a ball that weighs 1/10th ounce over/under, I think that is within tolerance. To say a ball 1/10th of an ounce over/under is easier to maneuver is horse crap. There are millions of other factors that come into play.
Edit- And before someone says, "That's just your opinion"... Well it is, and people saying the red circle is lighter is their opinion.