Even if the pool's hashrate falls, your expected BTC per your hashrate is the same. This is reflected by your estimated reward rising. Now, in a proportional pool, long rounds do suck, because they pay you less than average value for your shares. But we've had many quick rounds too, that paid more than an average one. The goal of ESMPPS is to even out your reward over time, and not feel the pinch of long rounds (or reap extra benefits from short rounds). We're working on it We are testing the code thoroughly, because when it comes to accounting for your BTC, you can't be too careful.