At least my other 2 units are working reasonably well (although they're now hashing at around 220 GH/s - consistently. Well below what was promised.)
So if you have 2 "other units" (I suggest you have tho S3s working normally, right?) why don't try to clone the SD card content from normal S3 to SD card of S1's controller? Maybe it will work? 
That's the kind of thing I'm thinking of, but not sure of the procedure to do that. I'm not put off by a challenge, just don't know where to start..
Well don't I feel like a right idiot over this. I was pretty busy yesterday and didn't have much time to figure things out further until this morning. I decided I would reflash the original firmware, and resetting the configuration at the same time, and check to see if it would work that way, which it did.
Then I went to upgrade the firmware to the later version posted at bitmain, and noticed that the file I was using and assuming was that version of the S3 firmware, it turned out it was S1 firmware I downloaded some time ago for some of those units I had.
SOOOooo.. I owe a big apology to Bitmain on that front. I was a little frustrated (a lot frustrated) by the delays and while I still stand by the criticism about their RMA process, I was certainly in the wrong about the criticism of receiving the 'wrong board'.
Long story short, I flashed the correct version of the firmware, reconfigured the unit, and it's now hashing at ~440 GH/s and I'm happier now.