Sorry, we thought we had the stats pretty close until the release of the new miner, although it is like 10x faster is is not nearly as efficient as finding blocks on the pool their has been about 2x as many shares increase versus blocks found since it's release.
I don't fully understand how the sieve and all works but I would imagine it is much better at finding blocks while solo mining.
The issue is because the new miner quickly dismisses primes below the asked for difficulty. Because you only ask for 13 merit shares your miners have to crunch far more primes instead of dismiss them. This means you will get far more shares with little increase in chance of finding a block. The 2 options I am considering for the pool I am to writing is.
1) Dynamically increase the pool difficulty depending on the current Network difficulty.
2) Add a difficulty switch to the miner. Depending on difficulty depends on how much each of their shares are worth.
Either way, you will need to increase pool difficulty in relation to network difficulty or you will just become less efficient.