I've succeeded in getting two of four sticks hashing unstably and unreliably but I have seen submitted shares. I can't say for sure what the issue is that gets the chip working haphazardly at about 10% capacity, because the breakout boards were pretty much all-or-nothing. Could be signal integrity issues, I really don't know but I hope that's not the case because if it's a result of PCB layout we got problems. The signal traces are between ground planes - at least they should be if the etch fab didn't get layers out of order.
Nicely done!
btw one of my first surprises was that the USB 5V was rarely exactly 5V ... and depending on the hub - under load it went all the way down to 3.5V. It looks like you're already beyond that with the bolted-down hub, but do double that just in case.
Another thing I had to keep in mind was very short traces to the USB connector - some hubs were very picky about noise there.
And thanks for the pics - keep that pr0n coming!
Did you hand-solder all components? If you did - you are a HERO! I didn't realize how much of a PITA that was until I started using soldering paste and (cheap) stencils. For example - this took me just about 2-3hrs to complete and was significantly less messy and nicer than my other hand-soldered ones.