TL;DR: This pedal rocks!

I really dig it, I've had a few chances to play with it at stage volume and it is great. I run a Mesa 400+ amp and the HB really works well with the tubey goodness that is the 400+.
My favorite part is definitely how subtle the drive CAN be, but when you want to crank the drive you can really get a warm dirt too. It also responds well to playing pressure, so the more you dig into playing the more drive you get. That makes it sound far more natural in my opinion compared to some other pedals Ive heard that are "all or nothing" once it is engaged so even if you're playing quietly ears bleed.
My primary bass is 18v active/passive, so with the active engaged it definitely gets more excitable, shall we say.

Roughly speaking, in active I can turn the drive knob down about 1/4 turn or so to get a similar level of drive as in passive. A quick swap to passive and A/B to my passive amp input and I can immediately drop between crunchy goodness and a subtle drive.
Most of what my band plays is Americana-ish rock so I don't need a "melt-your-face" overdrive...in other words, the HB is perfect! This week at practice I pretty much left it on all night and loved it. I think my guitards are jealous.
I still plan on recording some samples, this week has been full of surprises so I didn't get nearly as much playing time as planned.