And since you wind up paying an exchange fee anyhow (mined coins -> BTC -> Payment coin) I personally recommend just taking BTC and exchanging it yourself. This way you can control the timing better (worse case its a wash as your paying the exchange fee either way)
Suppose you mine ETH and want to be paid in XMR, the pool will change to BTC before changing to XMR!?
this pool doesnt do eth.. but yeah this is sort of what happens.. it doesn't necessarily exchange them to btc first, but it values the coins you mine at the btc exchange rate, then pays you the amount you mined vs that.
this is why if you get paid out in the coin you mine, say one of the algos that have only a couple coins.. you will always get less than you expect.. its not the pools fault. its so its fair to the people who get paid in btc..