I have the 100WPC stereo amp they built and the manual that came with it. I saw the little mono's for sale on audiogon earlier this week and they appear to just be a smaller version of the same thing. I can make a copy of the manual if you like, it does have some schematics and other information.
I did contact the guy who made them looking for more info when I first acquired the amp and he didn't really have much to say but I might still have his email address.
Ah, just looked at their website
and the one I have is the OTL-20, so the manual I have is applicable.
edit - I forgot to mention, I never had any problems with the protection circuit. I did trip it once when cranked up, blew a fuse but had no blown tubes afterwards. One thing I did notice what the B+ voltage is a bit high for the 6AS7G tubes, so I added a larger resistor between the cap banks. This dropped it from about 170V to about 150V if I remember correctly.