It is my understanding that the KTR is like the silver since most people who follow the Klon story agree that is the best sounding one. Many people who build the original circuit then go on make sure it has the Silver mods.
There was a DIY project called the "Silver Pony Pedal" which was based on it. They supposedly stopped selling it when the KTR came out.
Video shootout:
https://www.youtube.com/watch?v=IeuTQAn8_oQOn this site:
http://tagboardeffects.blogspot.com/search?q=Silver+Pony