I own a small business in Fort Collins, Colorado... we sell gyros (donner kabobs) to (mostly) drunk (mostly) college age people prowling the local pub neighborhood. There are about 21 pubs in a 4 block area in Old Town Ft Collins...
Anyway, I've seen these things in action, up close. We had a riot when the state hockey team, Avalanche won the Stanly Cup a couple of years back. It was kind of raging all around my cart, but my customers were all being cuccumber cool... weird and hard to believe, but it's true. Regardless of the freakishly civil behaviour of everyone I could see in line at the cart, we got targetted with a cannister of tear gas. It was ****ty: I had to throw away the food I'd been cooking while I was blind, then explain to the adrenalin cooked cops that I was one of the downtown merchants that they were protecting before they could beat me up with one of those "non-lethal" batons. Luckily one of the cops recognized me.
About four months ago, a dozen or so over-grown school children were having a fist fight in the middle of my line. I tried to break it up, but there was just too much momentum to it all by the time I figured out what was happening. I called the police, who showed up in less than 1 minute. They came running into the fray firing tippmann prolites one handed as they ran. they hit one of the pugilists and one innocent bystander. These two people were out of commission immediately. Most of the other guys who were fighting took off running, pursued by police trying to shoot a paintball marker with one hand. It would have been funny if it hadn't made me so nervous to se little puffs of pepper spray all over the place.
Still, the cannister sent everyone running, while the pepper spray balls only really seemed to affect people who were actually hit with them or people in contact with those who were hit directly.
First time that a lot of people had seen a paintball marker maybe, but I don't think anyone present in this instance would be put off if they weren't already. It was clear that there was pepper spray in those things, not paint.