Cool find! I saw something similar being demo'd a few years back but never tried them myself, just went out and bought a center stand instead, much more stable and convenient.
id like to have a center stand but of course it wont work with aftermarket exhaust. but this thing is pricey too its like 80 bucks :/ i have a rear stand but its useless at the moment, rubber on the paddles is destroyed and im not really sure what i can use on it now.
I have a Packjack. It's a total and utter fail. I've tried to get it to work many times, and I can never get it to fully lift the rear wheel off the ground.
The product is inexpensive, and the guy who owns Packjack was really nice. But the one he sent me just didn't work.