No scratches for me from the Jot Pro. The stylus itself is not going to scratch your screen. What can happen is that a piece of grit gets caught between the Jot Pro disc and the screen itself and that grit will scratch your screen.
But to put this into perspective, I'm in the construction business. My iPad 2 was on job sites where my "desk" was typically a piece of plywood nailed to a couple of sawhorses or more likely just a stack of drywall. It was exposed to grit and grime, sawdust, metal shavings and all sorts of stuff every day for almost a year. I had the Jot before the Jot Pro and didn't have a single scratch on my screen when I sold it. No screen protector either (which I find superfluous on an iPad personally). All I did was ensure that I wiped down my screen a few times each day and I typically used my Bamboo for normal use to keep the grit from my hands off the screen as well.
Trust me...the stylus itself will NOT scratch your screen. Grit trapped between it and the screen can and will, however.