SusieQOH, I think the gray does look odd when put with the colors, I guess because they are all warm colors, or because gray is kind of flat when compared to the richness of the colors. You could google 'quilts with gray background' and check the images; if you don't like the way those look, you could substitute for the gray. Several people on Bonnie's Facebook page are using brown, purple or dark blue for the gray.
Belfry, it's amazing what natural lighting will do in a photo. I think that contrast will be fine.
I pressed a few burgundies to add to my red.