Actually, i meant this ->
Another incorrect implementation is to pay all shares in a window given in units of time (sometimes called PPLNM or PPLNH). In addition to the problems above, it has a problem common to all reward systems that use time as a factor, which is that it is more profitable to mine when the current hashrate is higher than the average.
Please hop the pool, what you are saying is that the pool is more profitable if the hashrate rises. When you join, the hashrate rises, so basicly you're saying that everybody should join the pool.
There is a difference between theoretical exploits and something we should worry about... I consider all this FUD, while it is nice to know the underlying mathematics, and while there are real pitfalls to evade, some issues are irrelevant imho....