Look/Dynastar now have two versions of the PX binding out, they are the PX series and the PX race series. There are a few differences between the two binding systems.
The PX sereis includes the: PX 10 (junior) PX 12, PX 14, and PX jib.
The PX racing series includes the: PX race 12, PX race 14, PX 15 and PX 18.
You all know what the PX series are like (good for most but not great) The PX race series differs from these in a few places.
No Lifters: The PX race series do not come with any lifters of any type (shock absorption or traditional)
Fixed front AFD: on the regular PX bindings the front AFD slides, It is fixed on the PX race bindings.
No vertical Release (PX 15 and PX 18 only): the PX 15 and 18 toe piece is the same as the p-15 and p-18 toe piece.
Shorter Heel track: All of the PX race series have a shorter heel track then the regular PX series.
Worm Screw heel adjustment: When the switch to the origional PX bindings was made the forward adjustment system was switched to a lever style. The wormscrew style has been brought back int he PX racing series. (this is a good thing)
What these means to you (what bindings should I buy): In short if you are a more agresive skier or bigger switch to the PX race bindings. The Worm Screw is much more solid then the lever system, especialy for SW landings. The fixed AFD will also provide more retention then the sliding AFD. Not as safe but more performance. The Shorter heel track will allow the ski to flex more along its natural flex instead of against the binding. I won't tell you which din binding to get since that is an individual thing and up to you (be smart), and you should figure out if you want Vertical Release or not (are you a pussy?)
oh and there are some sweet deals on PX 12 racing and ok deals on PX 15s at
sierrasnowboard.com along with some nice pics 