I just did this Saturday morning. It was my second build. I decided to go ahead and add a distortion channel to it from the start. I used 4 diodes (1N914) to try to keep the level from dropping too much, and to not be so nasty.
I also wired in one of Orman's satuartion controls, but I need to put it on a dpdt mini switch. Since you have a lead to the pot, then one back from it, the switch is only cutting off the input to the saturation control, so the diodes are still kind of in the loop. Because of this, I haven't heard the clean side of it yet, but I'm going to fix it tomorrow, probably.
I also picked up some 1N279 diodes the other day. Are these Ge? I swapped them into my Muffer (the 1st build) when I was boxing it up, and they were quieter than the 1N914, and didn't seem to distort as much. They are also considerably larger (higher voltage capacity?). I figured that since a 1N270 was Ge, that these may be a derivative of those.
Sounds pretty sweet into a tube amp (it was a Peavey Classic 30).
Thanks to everyone for this awesome forum--I'm learning a ton about my new obsession.