When Triple Mining started, one of the advertising bits was "no poolhopping restrictions!"  As a way to boost hash rates and make the pool more successful, I suggested that MrSam implement something to take away the incentive to poolhop (such as a scoring system).  This has not happened, and with a pool of this size people can casually check and decide to hop without needing sophisticated software to do this for them. 

In my view, you can't fault people for doing what is in their rational self-interest.  All you can do is to remove the incentive to poolhop in some way, but as MrSam pointed out it is difficult to do that without also causing people to leave the pool altogether.  Obviously if everyone hopped, the pool would very quickly die.  This is why I feel proportional payouts are a negative overall, especially for a pool this size with its history (some *really* fast blocks and some *really* slow blocks). 

Taking away the ability to mine or to view the stats page (or even delaying the stats page) really isn't a solution, because it is easy enough to get around that.  A better solution would be (IMO) to implement a system that rewards people for not poolhopping.