Teri Lynn, I press with the paper on. I also use mary's best press and it hasn't caused any problems. The only issue I had right at first is that I had printed on a laser printer and the toner rubbed off on my fabric. Once I switched over to an ink jet it's been smooth sailing.
Honchey, now that it doesn't take me 7 hours to make one block, I can actually post them on time.