Imagine, if you will, a miner with cash costs of $250/oz (all...

Imagine, if you will, a miner with cash costs of $250/oz (all US$) and 100,000 oz/a. A year ago it would have not meet all costs (HO, capital etc) and would not have been drilling so X2 free cash flow would have been generous. It would have been a penny dreadful (parts of a penny?). But at $350 it is in the black. At $450 (assuming proven reserves) it can actually pay a div and X10 cap gains are easy. Much more possible.
Your best gains are, paradoxily, in high cost miners.
If you had US$s to invest there are a host of "out of the money" miners there which will be BIG winners and you would be on the right side of currency risks.
Yanks couldn't loose. Why do they buy LOK?