Large background stamps were some of my first SU! purchases many years ago. I still buy them and use them. When you look at the gallery or a stamping magazine, way more cards feature DSP and/or embossing folders for backgrounds than stamps. But, with stamps you can create your own designer paper and have total control over the colors.
I have a stack of background stamps that I would never sell.
Color Challenge guest designer for May -- come play with us every Tuesday!