ohhh ok, thank you but i dont see how its exploitable, without masses and masses of hash on the pool for long periods, not solved a block in 4 months but shares have stayed about the same give or take, if i had regular big hash power i wouldnt be running prop, but as its only a small pool, i thought it would be fairest 
There's a lot written on it, and it can be a significant profit optimiser for any miner on a proportional pool.
I had a whole blog about pool hopping proportional pools at one point, theres a post explaining it there (somewhere): https://howtohop.blogspot.com