If Brinks takes out the copper pennies, they do a horrible job by me. Brinks is the only boxes I can get around here and I average 25%-30% copper. I have heard the rumor they do it locally in some areas, but not nationally. But until verified, I will keep it as a rumor.
One of the tellers at a bank I get 3 boxes of pennies from every week asked me what I look for in penny boxes. She said the Brinks driver questioned why she orders so many pennies, after telling him she has a customer who searches pennies, he stated that "I wouldn't find anything in them, Brinks sorts all the good stuff out of them".
I'm still trying to figure out what good stuff they sort out, I have excellent copper percentages, do well with wheats, and had 2 indian heads during the Super Bowl week earlier this month. Those are all the things I would classify in pennies as the good stuff.