Anecdotally (which is all most people seem to be able to do with ski technology....) The tryolia site differentiates between the Light Diagonal (LD) and Race Pro heel with two animations, the LD animation shows lateral release (After upward motion) and the race pro animation does not show any diagonal motion.
On the tyrolia tech database linked above, the Freeflex 11 for example has the "PB LD 78" for the BRAKE which I take to mean it has the light diagonal HEEL. and the freeflex 15 and 18 have the "PB Race Pro 17-78" brake which I take to mean race pro heel.
If you scroll way down you will find that the freeflex 17 before 2008 lists the PB LD 78 "brake" which I take to mean the LD heel.
07-08 appears to be the first year the race pro heel appeared, and only in the 18x binding.
In 08-09 the 15 and 17 also took the race pro heel.
On the Fischer site, the Z17 is listed as having the "PB Pro 17-78" in the random list of features below the image, while the Z13 lists the PB LD 78.
For further confusion, the Z18 FF Race Service lists the "Race ND" heel on fischer's site, a term which does not appear in the tyrolia db as of 09-10.
This is mostly circumstantial evidence but its something.