I have the '10 (although I ordered the '09 which I guess is a score but dunno really)
As Si says, the difference is the damping system has been swapped out for the FIT cartridge. Allegedly this also shaves 100g from the fork weight although BikeRadar said small bump damping was stickier than with the 09 (but perhaps seals need worn in etc) but big hits are well dealt with (although I don't recall if they said this was a change from the already well considered 09 model). The chassis remains unchanged from what I gather so stiffness should not vary.
I would take the cheaper of the 2 (almost certainly the '09) but the MSRP is bonkers which is why I was made up to find mine half price 😀