With PPS, fee or no fee, you mine at a flat rate. So if, so called, luck is good you loose if it is bad then you win or least break even.
The
law of large numbers means that in the long run, you will never have consistently good "luck" anyway. The only potential gain from non-PPS is
short-term good "luck". Also, you don't
lose it by using PPS-- you simply don't get paid an unfairly high amount. PPS pays you what is "fair" for each share. Do you complain because blocks only pay 50 BTC, and not more when you're "lucky"?
On a side note Eligius really has some really messy site.
Feel free to improve it. Eligius is a community pool.