I find this pedal to be all right for that "Heavy Metal" Garcia sound that Jerry flirted with briefly in the late eighties. I never really ran into a problem using batteries in it, but then I never owned the original adapter, so I guess I just got used to it on battery power. Honestly, today's multi-effects units are so versatile when it comes to distortion and creating patches, I just use my Boss GTA-3 for any patches I want to create with distortion, overdrive, delay, and or Flange/chorus effects.
I will say that I have literally NEVER been able to get an auto-wah sound worth crap from this or any multi-effects unit, and I like the Boss Octaver (OC-2) for my octave dividing, though I never really tried to get good octave dividing from the GT-3, and I bet I could.
My point, in this tangential response, is that some effects, at least in my opinion, are somewhat generic in that you can tweak almost any good digital pedal to get what you like. I just have never really heard any inherent superiority of any of the top of the line distortion pedals over one of the others. Again, not talking about junk here, but Boss, MXR, Roland, etc. I think if you tweak most high end distortion, flangers, chorus, and delay boxes (digital or analog) these days you will get the sound that you want regardless of what Garcia or anyone else used.