I'm not sure on the answer to that.  It is interesting, though.  I think this block started during the jackpot day, so GHash/s jumped up to like 133, then slowy trickled down to its 40 GHash/s.  Those still mining are increasing their portion of the total number of shares, but those who left might be getting the benefits pool hoppers get (though presumably those benefits dwindle in a case like this).  However, at the end of the day it's still only 50 BTC to go around to everyone involved in the 120+ hours so far, whereas if three blocks were solved in 24 hours, that would be 150 BTC to go around.  That said, if everyone quit mining, the block would never be solved, so the longer (more shares) you have mined, the more you would have to lose by quitting.  When they go to PPLNS, this all changes, and only those mining within 60 minutes of the solution get anything, which would be hugely beneficial to those solely mining at triple on the rare monster block like this one (unless the timing of a problem screwed them over).