Matt Barnes and Wally Szczerbiak are similar players. Poor defenders who are not athletic enough to stay with good 3's who have good outside shots. Not quite sure where the misnomer that Barnes plays good defense came from outside of someone trying to give him credit for Stephen Jackson's prowess.
If they sign either, I'd be OK. Both are nice minimum level backups that are better than the slop we currently have manning the position.
Matt Barnes is a much better player than Wally. He can run, they both shoot the same, he defends much better (not lock down, but Wally is awful), he can slash a little, plays two positions, and even rebounds a little better. I agree this isn't a huge debate since this signing is a wash if Hill comes, but Barnes is a much better player than Wally.