I'm going to say none... but can't speak for him. They're a cassette style transmission like some other (usually homolgated) race replica designs, so you can slide the gears in and out simply... big advantage in professional racing but not in many other situations. I don't care much about it to be honest but Aprilia *really* think out the maintenance and functionality of their bikes.
I dont see the big deal, my 09 ZX6R has a cassette transmission that also comes out through the clutch cover very quickly and easily. And it came out in 09 on a much cheaper 600cc sport bike.. So its not like Aprilia invented the technology or are the only ones using it on stock bikes