PPLNS is the same concept, but it does not care about what point in the block chain it is, just what your share percentage is at that moment. PPLNSG is the same as PPLNS, but the pay is handed out in shifts, usually 20 minutes long.
Where this all comes to bear is how you mine. If you are going to be constantly stopping, for whatever reason, then PPLNS is not the way to go. As soon as you start mining, your share percentage goes up quickly and stays there, it then drops nearly as quickly once you stop mining. If the pool pays once per day and you stop mining two hours before that, then you will likely get paid nothing for that day, even if you steadily mined the other 22 hours.