Coin volatility is certainly an issue.  If you are looking for a pool without volatility, try my nbt/cny pool at http://nupond.net
The rate is 0.15%/day.  The main risk in that pool is exchange default.  If you want to support the pool on poloniex, you will be using nupool run by willy and wooly sammoth, which will certainly have btc volatility risk.  Try here: https://nupool.net