GMPP kit works very well where I live. I'm just getting to the end of the life for the shocks. IMHO it works better on the street than the Koni/ZOK combo. The Konis, are a 1 trick pony. You can dial them in for one type of conditions, but then they lack in others. I do not dispute that they work good AutoX, but you don't have potholes and other crappy road conditions in AutoX.
Wish I could do a test with the other kits because so far, on the street, I've been disappointed whenever I try something that isn't the GMPP shocks.