I bought a used one (GC) and it sucked. A/B'd it with my DM-2 and DM-3, and the Carbon Copy had a weird ringing effect at the end of the echo.
So I took it back. I paid $94 out the door, and it didn't have the box, so it really wasn't a bargain.
I now know there are two (2) pots you can tweak inside for the modulation. It's likely that would have fixed the ringing issue, but too damn much work. I'll stick to my DM-2's on stage and Dano BLT's (ten dollar, no holler) for road trips.
Play skillfully with a loud noise - Psalms 33:3
Madry Polak po szkodzie !