I have been lusting for that pedal for months. I anticipate that I'll run it with the dry and the Growl up. Don't think the Girth sounds very usable, at least in a live situation. Not really sure how (or if) I might use the mid boost. I supposed every little bit helps to cut through, but not sure where I'd run it.
All of this is based off nothing but really careful listening to demos of it on the web, so you already know way more than I do.
If you're still with me, I anticipate using it on higher registers. Perhaps in conjunction with my MXR envelope filter. I'm sure you've seen this video.
MXRBassOctave - YouTube
Near the end he fires up the envelope filter--dig it.
One of my bands is a pretty hard rocking group where I hope to use it to fill out the mix when the guitarist goes for a solo. My other band is a highly engineered trip-hop group where I hope to use it just to get weird, making some interesting bass lines in higher registers.