Basically, they use compressed air to actuate the shift rod, instead of you simply using your foot. The increase the speed of the shift and therefore increase the amount of time the bike is under power. Good for a few feet at the end of a 1/4 mile.
If you're roadracing - weight counts for more - There's electric ones that cut the ignition for a moment when you weight the shifter. They're lighter and just as fast.
On the street or for trackdays you'll need neither one.
It sound like a drag race product, since don't race or anything would it be of any use to me on the street? I don't plan you buying one, but simply want to know about the product. I saw a guy with a bad ass 12R (kawa) in Columbus, Georgia at Extreme Power sports and he had one on his bike.