As someone else mentioned in another it is more likely for them to attempt double spends by creating alternative block chains. I recently discovered that the pool I was mining for (ABCPool) was reselling their hashing power. On fundamentals alone I decided to leave the pool and go back to deepbit. I purposely went to deepbit because I think BIP 16 and BIP 17 need more testing before attempting to implement them. I wonder who ultimately is paying this 105-115% PPS and what their true motivations are. I suggest miners take a closer look at their pool to decide whether or not they support the actions of that pool.