I always assumed that to get the clean low, s and distorted highs you would still need two amps, but listening to a recent clinic I did hear him say "if I only had one amp , wouldn, t it be nice if I could get my bass tone, then just ghost in distortion" so apparently the splitting of the channels in the sig pedal does work.
I was just curious how it does this, I assume it splits the input in two , then allows you to mix the two channels and add comp and distortion, but the question is how, its very clever circuitry