I know some other users are reporting that things are OK on their pi's, but when I look at the pools stats for the same pool we're on, I'm consistently hashing 100Gh/s more with the settings I'm able to run on my Windows box. I'm not sure they're turned up all the way on their pi's.
I attribute this to my own laziness. I have all the stuff to make a headless rig without using my pi, I just need to put it all together and do it.