Slush's algorithm to reward later submissions with bigger value then first round entries meant by sheer luck I would get way too random results.
I agree!
I've been doing some pool shopping lately.
Deepbit Do to the number of miners, your "cut" of a block is smaller/more frequent, *usually* fees.
Slush's Roughly 16hr wait to validate BTC, larger/slightly less often reward.
This applies to all the smaller pools:
Infrequent rewards, but are usually much larger. You could be mining for 2 days before you get a block! That block may yield 2BTC+.
I've checked my 24hr averages from 4 pools (2 small/2 large), and what I see, is that whichever pool you go with, your rewards vary, very little, and balance out over time.