I highly discourage any of you from using Slush's pool, he cheats his users a lot, my mining client showed 40+ valid and accepted shares that just weren't counted on his site, (all were accepted and in a put in every other order so i got about 1/2 of my expected yeild) furthermore, the NMC mining doesnt work, and according to a little poking around, has never worked (which yeilds me to think hes just using our hash's and keeping the NMC himself about $1,231.78 per day at there hashpower) i commonly disconnect, and half the time my PC isn't being sent shares. Anyone else experience these problems? i moved to BTC guild and there wayyyyyy better. so much more stable.
1) Getting less than your expected yield is not uncommon on any non-PPS pool, especially when your analysis includes only 40 shares. Slush's pool tends to have extremely high variance for low speed users due to the scoring method. In the long run, it's expected to average out, but variance takes weeks/months to "average out". Using a very small number of shares/time for comparison will have a HUGE variance.
2) Slush's NMC merged mining was only ever implemented on Getwork, and worked fine at that time. However, Slush no longer runs any getwork servers, only Stratum, and he has not implemented merged mining via Stratum. Slush does not generate any NMC blocks anymore, thus does not pay out NMC.
3) Happy you like BTC Guild