I think a laser copy background is nice, and it 
can enhance the look of your cel, particularly 
when it's a cel that has what I like to call an 
"amputee" character (a character who is partly cut 
off due to being behind something or sitting on 
something, etc.) but it wouldn't make me spend a 
lot more on a cel, I'd only be willing to pay a 
small amount more.
I also don't like non-matching backgrounds, I 
really can't see much use in it, but then I am 
pretty anal about things.
Blair