Re: [8500 GH/s] Slush's Pool (mining.bitcoin.cz); TX FEES + UserDiff; ASIC tested
(...) Everything the same, a 6-hour round should absolutely pay better than a 1-hour. More work, more uptime, higher cost of running.
Why should it pay more? Whether it takes 24sec or 11hrs to find a block - at the end of the round it always brings exactly the same amount - 25BTC (currently).
Aside from that - I agree about the second part - shorter rounds are more profitable. But that's luck.
