We're missing something. To block withold attack of this magnitude (given the luck change) would have to be 2,000TH per pool. To do this to eligius and BTC guild for 2 months would not make sense unless they could profit elsewhere.
Not true. By going unnoticed and getting paid they only suffered a small percentage of the total payout as a loss. If they haven't fixed the bug by now, it is probably something wrong with the hardware and would be a total loss if they didn't scam unsuspecting pools. This is not a defense of their actions, only my attempt to find a root cause for the attacker to continue to block withhold.
The only people making hardware, writing their own software and mining at the ~2Ph/s scale that I am aware of is ______.
If this is the case and it is the pool with the biggest percentage right now, then they are after 51% and seek to undermine, control and possibly destroy BTC or at least damage the reputation.