Happy New Year everybody!

How good is middlecoin pool for weaker miners?

I've got two miners at different locations pointed to eu server.
Miner #1 is about 760 kh/s (7970), miner #2 is about 460 kh/s (6950).

According to cgwatcher, "efficiency" for #1 is around 95%, while for #2 it's 53%.
Is there any way to improve the efficiency of mining on a pool with a fixed difficulty using miner like #2?
Or am I missing some other factors maybe?

I also have a feeling that earnings do not have the same ratio as hashrates/WUs (both around 1.7) of the miners, but I need more time of uninterrupted simultaneous mining to be sure...