Hi SVL, I just built a copy of one like a week ago. Not an EXACT copy in that I externalized the presence pots so I have 8 knobs not 6, but circuit wise, identical even down to the exotic diodes.
I added the "gain" mod to one channel (which is just a pot value substitution, I might make this switchable externally. Super easy to do.)
My thoughts after playing with it briefly over the last week or so are actually pretty much in line with how the pedal is described by Analogman, but to elaborate...
I built a Tube screamer clone ages ago and just never bonded with it. I always thought they sounded way to thin with excessively "gritty" distortion. Ironically, the KoT in overdrive mode is basically the what I wanted a TS to sound like. Guess I was working with the wrong platform all along!
Sound wise I can immediately hear the Bluesbreaker legacy. Especially the clean boost mode (which is clean to about noon on the drive dial). You can play basically clean and when you dig in you get a anywhere from a tiny hint of hair to a 5 o'clock shadow. It just seems to suit (my kind of) bluesy playing almost perfectly.
I have the second channel configured as overdrive and as I said, it's what I'd hoped a TS would sound like. That kind of smooth fluid distortion that lets you hang onto a note for ages. There isn't a huge amount of actual gain there though and combined with the fact that it is quite transparent, it can sound a little thin compared to some of my other pedals as there isn't a wall of fuzz and/or distortion masking every note. That however, is one of the reasons I think they make great blues pedals.
Configuration wise they are also nice and flexible. Using the DIP switches you can set either channel for boost/OD/Dist mode meaning you can configure for say a nice OD sound and kick on the boost after it for a volume bump, or vice versa have a nice boosted sound, then kick in OD after keeping the same volume but adding more gain.
If I get home from work early enough tonight I'll see if I cant knock up a quick video for you.
If you decided for some reason to DIY, let me know and I'll tell you where I got all the bits from. The only build drama I had was that PCB I used looks to be a direct copy of the real deal, meaning PCB mounted pots and no other mounting points on the PCB. As I didn't want to PCB mount pots, I had to velcro the PCB to the case. Not my preferred way, but with most of the boards I have from this supplier missing any form of mounting consideration, I've learned to adapt.