Interestingly, I put a few erupters on a 10.7 mac mini with MacMiner.  Slow rates.  Spent an absurd amount of time.  Found that the Mac USB libraries involved in cgminer were the problem.  It took some digging. 

When I did a clean install of bfgminer, I had to install the Silicon driver.  It cleaned up my little USB driver mess probably by simply cutting them out of the equation.  Now it's rock solid.  Something to consider.  Picked up more than 20% on the units/min. I did use bfgminer 3.3.4 withnn -G -S erupter:all

I've noticed my new mac air with 10.8.4 doesn't have openCL but they are saying it is in 10.9.  We shall see.