I have 2 sub n up pedals - one regular, one mini, and whenever I use the sub octave, I also use the up octave - doing that makes things not just lower, but "bigger". The octave up top also helps cover up some of the strangeness that happens down low. Kind of a "look over here" distraction thing.
I tried running the up octave through a distortion - the thought was, if it's easier to get a good distrotion tone out of a guitar rig, maybe using an octave up shifted signal thorugh a guitar overdrive (and then blending it back in) would sound cool. It sounded....like a calliope or something. Not even close to the tone in my head. It might be useful for someone. I'm just not that someone.