Ellis I switched to Thunder Gray a bunch of years back because the foreground got really bright looking on a medium gray and it took more effort to get the background dark. It really depends on the piece as to which back ground I use. Often for work I post on WC it's just whatever back ground was up because I'm too rushed and I just use what's handy.
The goal in shooting work for artists who are applying to shows is to have the work stand out and not the photography. consequently my backgrounds and lighting are not too dramatic. I want the judges to concentrate solely on the piece because they may be looking at 1000 images to narrow the field down to 120 or so artists. They often have about 15 seconds to look at the image before moving on.
I went to a lecture by an artist who councils other artists on how to get into shows and he had picked one of my slides to use as a good example. considering how many artists he has seen over the years that blew me away. One of the audience members who knew me told him I was the photographer who did that shot. He said he liked it because it was very clean, not overly flashy.
Sometimes you need to use white, black or darker or lighter grays to make the piece stand out. How you light it also affects the color. When I light from above the foreground always get lighter. If I light from the front the background is usually darker.