Each share earns 1/400,000 of the profits. If the profits are 88,000 BTC, then each share would earn 0.22BTC.
Net is 90% gross - that sounds ok.
But I don't understand why you assume that Bitfountain gets half of your share profits. Bitfountain owns 200,000 shares which is already accounted for.
Your error in the beginning means you are off by 50% through out all your calculations.
Ah, that indeed is a good point. So the correct figure would be more like .05 to .14 rather than the .03 to .07 I proposed. There may in fact be some room for profit for those who bought at original .1 prices.