Past luck doesn't guarantee future luck...
Past luck dosnt affect future's luck at all...
On p2pool, it does. If all the miners leave because they think the pool sucks, and the main page says they are loosing 50% of their income by staying here, then yeah, past luck is going to ruin future luck.
You are mistaking variance with luck. I used p2pool for 6 month, variance over such a period is very small even with p2pool: my payments are currently equivalent to what I would have had with ~99.8% PPS.