Haha I've spent many hours researching pathys
From a few of the people running the king springs they have noticed that they sag early compared to other springs on the market. Other then that everyone has liked them.
From the research I have done, Lovells springs manufactured here in Aus seem to give the most lift (not quite as much as the AC springs you have over there) however it's significantly more then most others on the market out here and have not read any reports of sagging any more then the norm. I also havnt read any reports of topping out either.
These are the springs I have chosen to go with, so will be interesting to see how my setup performs when it's all installed as I have pieced it together myself.