I have to say that I'm in love with the new XF line from Skechers!  I already own a pair of "regular" Skechers Shape-Ups and I really wanted something lower to wear while jogging on my treadmill.  I decided to give the Accelerators a try and I am so happy that I did -- they are awesome!  The kinetic wedge seems to be a different material than the kinetic wedge in my regular Shape-Ups.  I don't know how to describe it other than it's more of a smooth, shiny rubber and seems to be more durable than the original kinetic wedge.  I have the light blue/silver Accelerators, but I like them so much that I'm going to purchase the black version.  Another thing that I really like about these shoes is the mesh paneling.  My feet don't get as hot in them.  I've also noticed that the insole is different from the original Shape-Ups.  It's a smooth material and has more perforated holes for breathablity.  I'm so pleased with these shoes that I won't go back to the original Shape-Ups.  These are fantastic for athletic activity and definitely more stable.  FYI -- I've found that these shoes run true to size.  Enjoy!