the s3+ firmware + the 4.6 cg miner has pretty much got rid of the hardware errors I was getting on one of my S3s. ok it was only 1.5% (according to Mantmonitor) now it's 0.0018%.
you can check the version via the api
if you are on a remote machine, from another copy of cgminer you can do the following command:
java API version 192.168.1.99
Where 192.168.1.99 is the S3.
Or on the S3 itself run
cgminer-api version
I have noticed bursts of hash rate significantly over 500 even though my frequencies shouldn't get the rate that high as I'd get an X in the row of os when using the higher frequencies one is on 237.5 and the other 231.25. just spotted one claiming 657.