This post documents a basic misunderstanding of the variance of Bitcoin. The past luckiness of a pool, or even how long the current round is, has nothing to do with how much you will make in future rounds. Every single time your computer trys a block hash, it has a very small chance of solving it that is always the same, a chance that is only based on the difficulty setting of Bitcoin. Your average earnings are completely based on how many shares you submit in a round, which is completely based on your hashrate. Whether you solo mine, or join the biggest pool, your expected earnings from your personal hash rate against this 'difficulty' problem will always average out to be the same. Only pool fees (and rejected shares or downtimes) can affect your expected earnings; and you can buffer against possible pool downtimes by running a second miner per GPU pointed at a different pool.
Your last sentence is kind of a lie. Pools go through waves of luckiness and unluckiness. I dont know why this is, but it IS the case. If you leave unlucky pools and join lucky ones you effect your expected earnings in a positive manner. For example, deepbit has outperformed bitcoins.lc everyday this week. If bitcoins.lc outperforms deepbit everyday next week, then someone who stuck with either pool will end up in a wash while someone who was at deepbit this week and bitcoins.lc the next will come out ahead.
Its all a gamble. When a pool pays me out below what I expect to get paid for my hash rate a couple days in a row, I usually check out the other two pools I am registered in and jump in right after a long round has just finished. I have noticed very long rounds are very rarely grouped together. Maybe there is no factual basis to what I do, but it has certainly worked for me as I have mined more bitcoins than all of the calculators told me was possible with my connection consistantly for each difficulty since I started mining.