TH1BTC is getting more an more interesting
BFL was shut down last week. I would assume they had 1) a large self mining operation and 2) their hosted mining operation, which were both probably shut down during the raid. I believe this has led to the drop in the overall hash rate, and that we might actually see our first negative difficulty adjustment in a long time.
Still, with estimation of average 9% increase over every difficulty increase and a 20% decrease next adjustment (thats very conservative number, buttf__king labs machines surely doesnt contribute 20% of the network), it would not be reasonable to buy any hashes. (you would earn 1.104 from hashing and 0.09 from interest assuming 0.25% rate)
Let's see how irrational it could go... lol just like on CEXIO
And as an FYI, I do agree with your math and statements. I have been following difficulty derivatives for quite a while now, and always see the securities being traded as being overvalued. This is one time where I think it is worth taking a closer look though, as we might be in a unique situation where the market is under valuing this security for the time being, and I do feel that there are unanswered questions regarding how the properly generate an accurate pricing estimate.