I believe you guys are assuming a BTC price per chip would stay constant. June chips wouldn't produce as much as May's and would not be worth as much BTC. Therefore price would have to lower and dividends would be affected. However, the USD cost is the same from month to month. If value of BTC goes up, there should be more orders and a premium price.
I think FC felt it was easier to give a range in USD and tie that to production costs. But, in the end it's 6 of one and half dozen of the other.
That is essentially pricing in bitcoin. If the USD price per chip increases as the exchange rate increases then it is the same as pricing in bitcoin. However, customers don't like to see their prices going up, so psychologically pricing in bitcoin is better if the exchange rate goes up.
However, if priced in bitcoin and the exchange rate goes down, AM makes less USD. Therefore, it is safer for AM to price in USD since their costs are in USD. Of course if you price in bitcoin you could increase bitcion prices if the exchange rate drops, but then you face that psychological problem again.
All this talk about pricing in btc vs usd is useless.
FC will sell the chips for exactly the max price people are willing to pay regardless of what currency is displayed.
What FC will never do (which many seem to think is an option) is pricing in btc without adjusting for btc value change.
"Psychologically" pricing in btc will return less profit than usd no matter which way the value of btc swings because it will either end up too cheap (value of btc down/less profit per sale) or too expensive (value of btc up/less sales)