You are missing the point.stand alone is for studio, built in is for live work .both TC/Ketron and prior Roland harmonizers do decent work (may not be studio ready).Hooking up to a rack or bringing extra pedal/midi cable plus no full integration is the problem.with built in VH,fine tune VH as a patch per performance ,save it to the song book ,etc, you are set.you can have doubling,female or male (2 or 3 back up singers following you depending on style or song. Try that with outboard gear without tap dancing, remembering and connection issues which may go wrong during live play.

You have to be a singer and true OMB to understand the concept/importance of onboard VH and how it's pros outweigh cons.