I thought they did a pretty solid job and if you follow Mike Perarra on Twitter, his feedback was pretty positive as well. He even said that the push in the back was for sure a penalty.
I actually liked the head ref, he was confident, clear and even laughed when one of the players ran into him during a call announcement.
Did you know one of the big sticking point in the negotiation with the refs is the league want to be able to "sit down" refs who are doing a bad job at any point during the season... you know, hold them accountable. They cannot do this now and the refs are fighting to keep it that way.
I say, until the refs give in on this NO BRAINER change, keep the replacements.