It's my understanding the the new spindle has a new geometry. In the video he specifically states a more aggressive "spindle".
Bret R mentions new geometry in this video.
There is also a video somewhere of Bret R with an Expert on edge on a concrete floor showing how the geometry allows the ski to pivot without resistance on the floor (while on edge). The new rubber alone wouldn't do this on a concrete floor. Why would retool for a new spindle if the rubber did the same thing? Time will tell...
Might have to schlep myself down to the dealer and see if I can compare the two spindles. Lots of conflicting information out there right now