Yeh, listened to the demos, I can see it would work for some singers with no backing vocals, but for me that wouldn't work at all. I am a backing singer and as such I don't do a 3rd or 5th etc of what the singer is doing, I do a contrasting line so for instance I can be going up when he is going down, or just on one note etc, so if I had a harmoniser on that it would enforce the backing over the primary vocals and not work well. I can see as one of those singer song writer acoustic acts or country or a solo singer in a group it would be good. Like all of these things, it really is group dependant
I would add, the up down in the H1 demo is exactly the same as the VoiceLive 2, and sounds the same as the harmony mode, just quite a bit cheaper, i have one but just don't use it for the above reasons, and pedalboard space.