Considered by some as "The Poor Mans Klon" (almost certainly because of the colour and form, they were obviously expecting a rip off), this is another effect which may not be the most fashionable, but sounds great to me. And you never know, if someone puts the effort in it may be a good base to start from for the next "big thing" if people can ignore Tubescreamer or Big Muff clones for a while! :o)
Buffer into gain stage into buffer means that at least circuit-wise it's nothing like a Klon, but definitely worth a build.
Info about the original:
It dishes out a superb blend of light overdrives that enhance, without changing, the sound of your amp. A unique "Pre-Bass control eliminates problems with too much fuzzy bass, or the opposite problem of being a weak, thin-sounding overdrive. Drive and level controls offer further shaping options. It's like having an entire arsenal of overdrive pedals in just one box. Add an entirely new dimension to your amp with a maximum 30dB of gain without overprocessing.
Light overdrives that enhance, without changing, the sound of your amp
Unique "Pre-Bass control eliminates fuzzy bass and weak, thin-sounding overdrive
Drive and level controls
30dB of gain without overprocessing