There's no doubt that it's a drawcard to miners because of the lack of variance in pps mining, making it a good way to attract miners. But history has shown that it is unsustainable in the long run no matter how large a pool is (even f2pool aka discus fish will eventually drop it I'm sure). It's a lot like the "doubling" odds people take on coin toss, red/black roulette odds etc - the fact is that eventually there will come a time that the odds will be so bad for you that you lose. Even if you were the entire bitcoin network, it might be impossible to safely run PPS indefinitely. OOC did an analysis of it a while ago if I recall correctly saying how much the pool operator had to have in reserve to run PPS and the associated fees required to make it sustainable according to risk. Pools that ran SMPPS thinking it was safer basically realised it was not and abandoned that in favour of a less risky payment system. I can't find the PPS link right now but here's the smpps discussion:
http://organofcorti.blogspot.com.au/2012/04/32-risks-of-smpps.html