I never used Mt.Red, but it's PPS,
so it might just be, that the difficulty of accepted shares on it is 2 while it is 1 on other pools.
At least that would explain the difference, you only get half the shares, but twice the reward.
Can you elaborate on that a little bit please? I thought difficulty was a fixed constant that changed every (2 weeks? not sure on the exact timespan).
From what I can tell I seem to be earning BTC at a 2x rate at Mt.Red. Literally twice as much BTC per unit time. I may be delusional but it looks like it...