Divine Wings backing vocals / choir

Uh, why would it be so hard to believe it's all Russell? You don't even need computer technology to do that. I think it would be very strange if they used a "real" choir. No one has ever wondered if Queen really sang on Bohemian Rhapsody, only because you can hear all the distinct voices. Symphony X just did the same thing, only one guy did the work of (in Queen's case) three.
 
Sounds like Russel to me too. The Dies Irae parts on V and Lacrimosa are all Russel too, from the sound of it. He has a very distinguished 'choir' voice. I've never seen them perform it live, and have never seen them with Miller in the band, so I wouldn't know how well he sang, but he is credited for background vocals on the album (s).