That's a good question. Your money stay in the pool until you take it out, but you earn interest daily. Your interest will be in the currency that they generate the most of for that day, or it could be that it will be distributed proportionately among all the members of the pool. So, for instance, if 10 people are in the pool and the interest earned today is 90% BTC and 10% ETH, then everyone's interest is divided proportionally so that each pool contributor receives BTC and ETH according to how much they contributed to the pool. That's my understanding.
The situation you bring up is a good one, though. When you decided to pull your money out, will it be in the currency you put in? I don't think I read anything that said. I'll see if I can find out, though.
Ya cause if it is isn't I wouldn't put in any BTC. But you could still do well just putting in a lot of their tokens. I would think that their value will rise if this exchange is popular. The one think i don't really understand is how the pool makes them money. I do see how the exchange would make money but what are they doing with the pool cash.
From what I can understand, the pool is there to help investors who want a little more privacy in their investing and who don't want to move the markets by dropping huge sums of cash in at once. The pool, being liquid, won't move the market as much with a huge investment. So the cash in the pool helps the exchange facilitate big trades. So if investor A exchanges BTC for Dash and Dash goes up, the exchange wins. They'll pay pool contributors interest in Dash. That's how I understand it.