i had one for a very brief time (2 months), and when I had it I lived in an apartment and couldn't crank it. Based on that limited experience, I liked it. I did feel it lacked the mids that I like; upper mids. But I was able to boost them via an mxr 10 band in the loop and with a ts9 up front. I also felt it absolutely needed an od up front to tighten to my taste. But again, I never got to wind it up.
I recently had a D Moll and did not like it at all. Way too soft & slow on the low end for my taste, even clean boosted with various od pedals. And the mids were too low mid oriented for me. I like that upper mid grind, and both the D Moll and the Herbert lack that.
All that aside, I would like to give another Herbert a go again someday now that I'm back in a single family home and can play at stadium level volumes if I want. I'd like to get a true sense of what it's like wound up.