It may have been a miscommunication; this is what they said:
I'll double check, it may indeed be the case that everything is in BTC regardless of the way in which you paid for it.
That sounds correct. Rather, that better be correct, or else I'm going out to the garage and grab my pitchfork to join Cedivad!
Although it was a bad call in retrospect, I considered buying BTC instead of making a Batch 1 order, back at then end of August. I would have made quite a bit of money by now.
It was specifically that element of the MPP - that they base calculations on BTC - that led me to commit my USD to Hashfast, that made investing in the hardware seemingly attractive compared to just buying coin. The MPP would, in effect, account for a rise in BTC value by counting my investment in BTC from the day of purchase.
Anyway, that's a biggie for me. But I think we just had a miscommunication here, my understanding from the beginning is the MPP is BTC based.