Love your piece - so cute. I like them to match as close as possible but I use rayon embroidery thread so it 'pops' a little. I've seen the black done and it's very effective.
I had a close look at my avatar quilt and would say, on balance, where there's not been an exact match, I've gone slightly lighter. This may because of the type of thread I use. I also prefer blanket stitch as I find it much easier and not so dense on the small pieces.