I intended to do the same thing... black background/white background. Both look great, but I sure like how the black makes the colors POP!
Yeah, I've never done a black background and I thought this fabric would be good with it. When I started I wasn't sure I liked it, so I decided to make white as well just as a sanity check. I like the white, but I really like the black too and don't think it was a mistake making it w/ the black :)