Couldn't I theoretically switch to pay-per-share any time my pool has taken a long time to generate a block to get a little extra BTC? It seems like the value of my shares goes down when we're working on a block with a lot of previous shares. If I switched to PPS for any block that had more than 110% the number of expected shares and then switched back to proportional, I could make more than expected.
What do pools do to combat this abuse? I know deepbit delays publishing the found blocks for an hour, but couldn't I get that information on block explorer? I suppose they could use a different address for each block, then I wouldn't know for sure that the block belonged to my pool. But in that case I could still switch to proportional anytime there has been a lull in the entire network's block production. It wouldn't make as much, but still some.
Has anyone tried doing this? And would you consider it abuse of the system? Is the difference I could make not really worth it? It feels to me that I could raise my earnings 20% or so, but I might be overestimating.