I've only got one board, but it has run fairly stable since it was repaired, albeit with 15% HW error.  It still puts out a consistent ~20 GH/s at int:52:2:950.   My downtime is more caused by ISP outages causing CGMiner to freak-out than by anything else.   Mine was repaired in the UK by Milkbottlec.  I never ran it before sending it off for repair.   It's made 0.24 BTC since I started mining in early Jan.  Far away from break-even at today's BTC prices. :-)

I'll count myself lucky that I only got the one so aren't having the mutiple boards problems.  

It seems obvious to me that maybe the problems you all are having is the quality of the repair itself?   Have you considered having them resoldered or re-repaired again?   Is anyone at Drillbit responding and could maybe speak up about the design and/or parts that should be needed to fix the initial problem?  I'll admit I haven't read every message on the Drillbit Forums but I don't remember anyone but the 'repairers' being told what the parts were / what the issue was.