Re: [850 TH] Slush's Pool (mining.bitcoin.cz); TX FEES + VarDiff
By extremely short blocks, you can't account for mean orphan probability. By a two-second block, probability of orphan race is extremely high, near to 100% IMHO, as the time differences between the good and the orphaned block normally are of the same size as is the block duration by a 2-second block. So I think you must leave out your "60" multiplier.
Good point - the odds still work out at around 1 in 1000000, but as Terry Pratchett once wrote, million-to-one chances happen nine times out of ten.
I still wonder if the contents of some blocks can make the difficulty vary significantly from the assigned difficulty though. Perhaps there is a weakness in (double) SHA256 where hash collisions are more likely with certain values?
Maybe OrganOfCorti can help us out on this one? Any crypto experts around? Where's Bruce Sterling when you need him...