Good news is  it looks like one of the big miners has stopped mining, so things look to be stabilizing nicely now, that is all it takes, I do know how hard it can be for a pool to control, an example would be 100 users total # rate say 120 MH/s and they have say 35% of the network # rate, but then 1 user jumps on with 80 - 110 MH/s pushing them well over the 50% share, all they can do is lock registration for this reason, I think members with high # rates have to just keep moving around as & when needed as big a pain as it is for them to do, all this can happen so fast, it is not as if a pool is going to ask 50 users to move pools while the big fish eats, by the time they do everything can change again, nature of the beast.