Edit: It's easy to misunderstand the PPLNS part. The sentence would be correct as: If i only find shares every 5-10 rounds then i won't benefit of PPLNS's "luck equalizer" effect.
Qwert brings up a good point. If you have very stable hashing rate, then PPLNS is fine. I find that my hash rate varies by +/- 10%, and diff 512 can make that worse. In some pools I was in, my payout rates were 97% because of my natural variance, when it should be over 100% (benefit from other people coming and going).
Is there a way to modify PPLNS so that the variance is not as big a killer?