STEEM price and SBD price changes affect how much you earn. STEEM price changes change the amount of STU paid out. And SBD price changes affect your $ payout when you receive the SBD.
We give profits in each vote and basically you get the same STEEM and SBD price fluctuations, but locked in for 7 days.
I'm reasonably convinced that there's more exposure to the price of USD while in a post than in just holding STEEM or SBD. (Not sure if that's fundamental or a side effect of the broken SBD peg.) But I'm aware there's nothing Minnowbooster can do about that, I was just hoping it might be a question you already knew the answer to.
I will keep plugging away at the math elsewhere.
Hmmm, not sure. 50% of the investmen is in STEEM anyway, so that does not fluctuate much. But the 50% SBD fluctuate heavily.
I mean the formula is pretty clear, just put it into a spreadsheet, plot a few values and compare to just holding steem or sbd ;)