Have you tried setting "Minimum difficulty" for your worker to 512? Some people reported that it helped if the miner did not switch difficulties.
Speaking of which is there some sort of tuning guide for the new options and/or bfgminer on bitminter, or is it all buried in this monster somewhere?
The post DOC did on the new options are back around page 230 +,- a few pages. i don't have time to look back. got to go to work. good luck.