So what I'm ultimately interested in is pretty divergent from the Motown piece. I just thought the idea of getting a clean guitar DI into the DAW was a common goal which is why I stepped in. I understand that my other goals are above and beyond what the Motown box does.
I see what I want in three blocks:
Block 1 is guitar input to DAW with a split to feed guitar world.
Block 2 is DAW to guitar world.
Block 3 would be guitar distribution fed from either Block 1 or 2 that would feed 1 or more amps, flip polarity, mute, etc.
Anyway...Looking at this:
http://cranesong.com/Volts to dBu to VU Comparison.pdf
And realizing that for some guitars the output is ridiculously hot, for my block 1, perhaps what I want is pretty much just a unity gain guitar input to line-level impedance converter? That seems like something that could be done without too much fuss.