Wow thanks for all the suggestions/input. Personally, I lean more toward something very programmable, so that I can just find a couple-few great patches that are usable - I'm not a preset kind of guy, unless there are a lot of them. I guess maybe because of latency these sounds can't have the "attack" element of some great synth samplers...
That first EHX unit looks great - it's encouraging that it mimics both the Prophet-5 and Taurus, which happen to be my two 80s analog points of reference that I had in mind. I once saw the indie band Celebration play in Brooklyn with a Taurus for bass, and it blew my mind. Like I said, I have zero interest in the patches that sound like effects, I just want a fat, synthetic 40hz happening.
I know man - I've always been tempted to try midi, but I don't want to spend a ton to get what you need to have fast tracking, and then get bored with it and have to sell it. I guess with these analog filter types the latency is the bottleneck, but I wouldn't mind playing from, say, the A (110hz) up and pitch shifting down. But it's a temptation to do midi and get instrumentation like...
The Source Audio C4 is pretty much infinitely programmable. But it’s also easily used with presets — just plug it in to the USB on your computer or into your smartphone, and load your favorite six user-made presets. Then you’ll have six presets right there on your board in a standard size pedal.
No need to keep it hooked to anything, once set, it becomes a standalone pedal.
(But you can of course set it up in more of a Source Auido ecosystem and have many many more presets and multi-pedal presets etc.)
Here’s one of the settings. Improvised jam with my band’s guitarist and some other friends.