I agree that the average rider probably isn't going to be able to notice any significant difference—and like you said, likely 90% marketing hype.
I really like my older RP23 and have the bike in the shop this week getting both fork and rear shocks serviced and one of the mechanics brought it up. Don't suppose he has any "vested interest" do you!!!
On the other side of the coin, the last add-on the shop recommended for my Ibis Mojo was the suspension "Lopes Link" and I really have to admit I noticed a marked increase in stiffness in the rear triangle.
Anyway, being a little skeptical thought I would ask around to get input from anyone who has it. I have read a few reviews and nothing negative–but they aren't always the most un-biased either.