The first time I created a white out on a quilt by somehow deleting all colour from the applique blocks, it was the biggest mistake I had made for quite a while, but I loved the result. This is one of many designs I now have in an assortment of project files with the applique all in white.
I think if I made one of them I would use many shades of white rather than one fabric, but keep them all as plain and white as possible. It would be a challenge just finding the fabrics … much quicker to go into a quilt shop and pick one fabric and buy several meters, or yards, depending on which country you are in at the time!
The quilting I would use just one white, though even then I would have to choose between thick or thin thread!