There's probably some work to be done wrt providing the statistics necessary to verify everything is done honestly. It will probably be easier if the pool switches to a lower variance method.
I don't think it's that complicated to make sure everybody is getting what they deserve. And no need to police this. Instead, if you have been contributing to the pool in the past hours before the block was found, your reward can be estimated by 50 * your hashing power / total hashing power. I think Inaba even implemented the correct estimate on the EMC website to avoid surprises.
Of course this method does not give you an exact number for your reward, so it does not make sure *all* rewards are paid up to the bit-cent.
I'm not sure I like the PPLNS method so much, as far as I can see from mineco.in. They estimate your reward by counting your contributions to the last 750,000 shares. With making the window so long, I'm not sure if this pool has much incentive for people to keep mining continuously. Although, currently its total hashing power is about 80 GH/s, which exceeds EMC's. I wonder if they can keep this consistently. And I did hear they had some long blocks recently.