Slush is currently working on a payout system that either eliminates this problem, or comes very close to it. He said himself he is hoping to have it in place in a few days (only 4 posts back).
The new method eliminates the possibility of pool hopping completely. There is no possible way to mine it strategically. See the thread on DGM: https://bitcointalksearch.org/topic/double-geometric-method-hopping-proof-low-variance-reward-system-39497
Oh, wtf. I switched to slush specifically because I thought the scoring algorithm made it unprofitable to pool hop. D'oh.