They sound noticeably different. If you get an OC-3, try the Guitar input, use POLY mode and turn down the range to 11:00-12:00. That will octave anything up to about the 12th fret on the G string and nothing above that. So you can slap and only the fundamentals get octaved. I wouldn't even bother with the OC-2 mode on the OC-3. It's okay, I guess, but definitely not an OC-2 clone tone wise.