Got my Skreddy BC109 the other day. Holy ****************! This is not for sissies! I didn't have a lot of time with it so far, but for now I can say: HOLY FUZZ!!! I plugged in with my Jazzmaster and was digging the variety of sounds. In the single coil mode, things were bright, fuzzy, and awesome. In the Humbucker setting, things were slightly tamed - a really cool feature. The Bias and Voice knobs definitely allow some cool variations of the sound.
I do a fair amount of DIY stuff myself, but have never built a Fuzz Face. I love the versatility of this thing. It's crazy fuzzy, ugly, noisy, in-your-face, etc. Basically, if I understand it correctly, it's an unapologetic version of a Fuzz Face... but w/ some slight mods/versatility that keep all the integrity of the FF sound, but just adds some versatility. If you want that sound, this is the pedal. If you want something more tame and controllable, you will probably be disappointed, so DO NOT bother. I still need to put this on my board to see if it works for my current projects, but if you are looking for that FF sound, I would recommend looking into it. YMMV.
Feel free to ask questions, but like I said - I don't have a lot of experience w/ the FF circuit; so hopefully Skreddy will chime in. I will say this: I've built my fair share of pedals. And I've been lucky enough to own my fair share of custom Fuzzes - including Skreddys, HM v3, Montgomery Appliances, and Stephen Douglas (formally of Skinpimp). So I'm not exactly a noob. In the meantime, I don't see myself in any rush to flip this pedal.