Proton you are spot-on. I just bought this pedal for my bass. I was greatly impressed with the phaser/flanger sounds and modulator/undulator. But really I bought it for wah and filter sounds and they stink! The volume drops, the frequencies affected are terrible. Yes, perhaps its the voicing, I'm not sure. I can't believe that a company of such thorough features and quality would even introduce the presets on this pedal labeled as "wah", given every musician's perception in the world of what a wah should sound like!
I hope with spending some "tweak time" on my modfactor I'll be able to get some more decent sounds out of it and crossing my fingers that some updates will heal some of these woes.
Still a fine piece of machinery though.