Interesting Bet. gmaxwell, are you willing to change the bet to be X BTC to be equivalent to the current price of the miner ($5999)? 8 BTC is currently around $6700, so the odds skew as BTC price goes up.
I'm not interested at 8 BTC, but if the $6000 equivalent goes to 5 BTC and the difficulty stays roughly the same, I might be willing to take that bet, for example.
I'm willing to twiddle with the terms, though under alternative ones I'd probably want more than just the 8->5 changed. Keep in mind that changing exchange rates doesn't change the BTC I think it will produce much.
If BTC were to go to $10000 over-night and I thought it would stay there, I'd be buying April machines myself for 0.6BTC.