And now, the Selective Inverter is finished!
It is a really crowded build. Getting the banana jacks on there was tough, as the nut drivers didn't cut it - I had to use pliers to get the nuts tightened. (Of course, that's what I get for having all those multed jacks in a banana system! But, I don't mind.)
One thing that I didn't realize from the description, but suspected from the schematic, was that in the fixed mode the "B" output is always inverted (i.e. the trigger inputs do nothing). Also, I was really confused at first while testing it, until I remembered that the offset voltage is bipolar (-10V to +12V). Anyhow, I'm very much looking forward to trying this out with some "real-world" applications!