Unfortunately the price of Bitcoin on Gox is influenced by a lot of other factors like some people thinking $ will be easier to get out in a bankruptcy, people trading the money they can't do anything else with etc.
When you could move BTC and the price on Gox was 15% higher than Coinbase I am sure you would not make the conclusion that BTC on Mt. Gox was 15% safer than on Coinbase because you would get more coins on Coinbase for the same amount...
I would use the following method to price these deals:
- MtGox was 15% higher when BTC worked and fiat worked
as well as it supposedly does now (there is no evidence that any fiat has been sent out since long time but let's believe there is). Since coins had the same value as in Bitstamp, we must conclude that GoxBux were appraised at 1/1.15 = 0.87.
- Now neither works. So we take the discount of GoxBTC relative to BitstampBTC (currently 570/642 = 0.89) and multiply it with the purchasing power of GoxBTC: 0.89*0.87 = 0.77.
We can conclude that GoxBTC should have 77% of the value of BitstampBTC.
Prior to DDOS, BitstampBTC was = blockchain BTC. If you believe that the DDOS causes BitstampBTC to be in a discount, apply this discount to the equation, which results in a slightly lower value.
