Nearly a week later, and it happened. The Doom Hammer lives up to its name. I bought it for my guitar board, and was very much surprised by it. Generally, I'm not a fan of "all the gain" type stuff (HM-2 notwithstanding), but this one seemed different. It's much more usable than I expected, and kinda bridges the gap between HM-2 and Muff. I have absolutely no experience with other op amp Muffs, so I can't comment on how accurate it is to that era, but I'm really digging it.
It's got more bass and fewer piercing highs than an HM-2 (which I like!), but is also slightly looser and with fewer highs overall like a Muff. I'm really digging it for an HM-2 alternative, which is NOT what I expected, though I had heard some reviews mention its "saw" qualities. Of those, I seem to get into "saw" territory earlier on the tone knob than others (I get it around 1:00, others have mentioned 2:00-3:00 or so). Perhaps I'm hitting it with hotter pickups - Black Winters and Nazgul/Sentient combo - or maybe it's my solid 30 year old state Peavey rig reacting differently than the tube amps and fancy stuff that the demos used. Whatever it was, I'm not complaining. I've got it about 10:30 on the gain, anywhere from 10:00 to 2:00 on tone depending on what tone I need, and volume as needed (which is much higher than expected at 2:00ish, but still has plenty of travel left). The tone knob seems to be the most important knob, as anything past (+ or -) what I previously mentioned gets into unusable territory pretty quickly for me. Currently at about 11:00 on the tone knob, it sounds like a much gainier version of my Priestess - which I'm definitely enjoying. At 1:00 or so, it becomes a bassier At The Gates/Amon Amarth tone. Jamming to those songs sounded awesome - if you like those tones but want a bit more bass or slightly looser, this is a great fit.
On bass, I'm also rather surprised. It doesn't quite have the versatility on bass as it does on guitar (not that it's incredibly versatile on guitar, just LOTS of gain!), but it's very much usable. I use the same settings as mentioned before, with the tone usually around 10:00, and probably never above noon. With that tone setting, I don't notice any bass loss. I think the added gain just heaps on so much distortion, mid, and high end content that many people might think there's bass loss. But really, there's just a big spike in the other frequencies. For all of the extra gain and compression, I find it way more dynamic than I would have expected and far less noisy as well. I feel like my B3K (which isn't exactly quiet) is noisier. Anyway, I'd say it's very much usable for S/D type stuff on bass, and I was not expecting to enjoy it as much as I did on bass. I had assumed it'd be one of the fastest "nopes" on bass I'd ever had, as gobs of gain are NOT my thing on the low end. But instead I found myself happily jamming along to Sabbath and Metallica, and while it clearly wasn't the original tone, it was a workable one!
Anyway, I'm happy to have added this to the arsenal. Now, I may need to find an(other) affordable Russian Pickle. I think I may finally have started to enjoy more gain on my pedals the last few months. (What took me so long, hanging out in this thread all these years?)