If I can get a smooth, scratch-free surface that is ready to apply finish, I'd rather spend the extra money on other stuff.
I've only tried the shop rolls from this source, but am getting ready to place an order for my 6x48 belt sander. I talked to the owner, who said the shop rolls are made for sanding metal and may clog a bit faster than some papers. I have turned about 40 calls and as many strikers so far using this stuff and am happy with the quality. It tears off easily, and I can count on using about 4" of the 1" wide roll per call or striker. I use it as a transition between 120 grit garnet emery cloth and 320 grit J weight emery cloth.