What to set pool difficulty to?

Hello,

Long time lurker, finally decided to register and pose a question.

A couple of friends and I have created our own pools and have been mining (ETC) fairly successful for the last couple months.
Our payouts have doubled the various payout calculators on the net.

With the difficulty dropping and the network difficulty dropping I was hoping we would be finding more blocks, but that hasn't been the case.

So the question is what do we set our pool difficulty to give us a better chance of solving and finding blocks?
Our pool is based on open-ethereum-pool and I believe our current pool difficulty is et at 2,000,000.

On our ETC and ETH pool we average 500 - 800 MH/s.
We've found 46 ETC blocks since 8/24.
And we just started up our ETH pool since the latest drop in difficulty.

Any insight would be appreciated.

Thanks in advance.