Been thinking of picking up a rat of some sort to use with my BD-2 as well. With the Mr. Vermin I read a couple reviews that the gain knob is finnicky and moves too easily to set nicely for low gain stuff . . . have you had any issues with this?
No, no issues, I feel like there's a low to mid gain sweet spot and you just learn to recognize by ear and I have no trouble hitting it by sweeping the gain up from low until i hear the amount of saturation you want. I'm using the lower half of the gain knob, with the volume set to boost, 99% of the time so take that for what it's worth.
some people use it with more treble and gain and less volume, perhaps in those territory it is more finicky?
I'm using into an already just slightly crunchy sound that might be compressing and masking what others experience, I also thought of that. maybe if you were dialing in on a twin reverb it would be touchy?
the rat is what I use for darker and edgier low crunch to kinda wide saturated mids with a touch of fuzz when the volume is up so keep in mind I'm also setting it to a point where it's kinda saturated and finding sweet spots with guitar volume knob which is only as touchy as your volume knob!
the pots feel solid, smooth rotation and you can feel a little resistances to turning.
edit also I gotta add, cuz I sometimes turn it on in tandem with the bd-2 there's an easy way to identify the sweet spot for me Turn on the bd-2 with your settings, I like the knobs at noon but volume at 10:30. Turn your guitar volume up to max. Kick on the rat. Does it sqeal? Too much gain. Back it off until it just stops. That's the sweet spot.
Now back the guitar volume off a touch that's my kicked up lead sound. The rat color fills in and compresses the crap out of the bd-2 and ads mids and cuts bass, for me the perfect complement
Kick one or the other off for crunch and guitar volume back for dirty cleans.