PPLNS isn't terrible even for intermittent miners, so don't be scared away from this payout system if you're the type who only mines part-time.
Before I did my own simulations (
www.calindora.com/tmp/bitcoin/index.php) of various payout methods, I wasn't much of a fan of PPLNS, as my first instinct was that it would overly punish intermittent miners. (However, a cursory examination will show that the expected reward for a share in PPLNS is the same regardless of the time it was submitted.)
However, after doing all that research into the payout systems, I think PPLNS is probably the best system overall so far. (Geometric is close, but running a 0% fee pool with low variance for intermittent miners puts more risk in the pool operator's hands.) Its variance is a bit high, espeically if N is low, which is why I favor an N of either the difficulty or twice the difficulty, but it's pool hopping proof in any case.
