Yup. I might expect any new ones to sport a 'designed for Rapture Pro' tag and state clearly whether they are backward compatible or not. All legacy Rapture an DimPro packs should be forward compatible.
(to be sure of a quick fallback position - secure an initial backup and/or esp LFOs, MultiSamples and Programs).
 
For an excellent freebie (more than starter) put on Muz3um for Rapture from PatchArena (courtesy of Francesco and Chad).
http://patcharena.com/synth-resources/cakewalk-rapture/

You quote of $99 for Dim Pro?  seems way off  as I bought it a year ago from Cakewalk store for $14.99 
At the time I had X3 Studio which only had Dim pro LE. So must have been an upgrade price. I imagine $99 would be for someone who did not have LE already. 
 
[Special] Cakewalk Dimension Pro 1.5 (Download)


Upgrade Selection: Dimension Pro for New Customers$14.99

Another question ... Z3TA+2 is not the same as Z3TA+ classic that comes with Platinum?
 

Cactus Music
You quote of $99 for Dim Pro?  seems way off  as I bought it a year ago from Cakewalk store for $14.99 
 

Dimension Pro comes with Sonar Platinum ... $99 is for the Rapture Pro upgrade.
 
Cheers, Rob.
 
 

Rob Ainscough
Another question ... Z3TA+2 is not the same as Z3TA+ classic that comes with Platinum?

That is correct.

Thanks for clarification ... I do wish Cakewalk would make this a little more clear in their "Comparisons chart".  I realize it's marketing "look at all these extras you get" ... but for "Platinum" (top tier) I'd rather not have hunt and search and try to figure out what is and isn't a "true" full version .... maybe add another tier "Titanium".
 
Thanks for all the help, appreciate it.  I "think" I'm sorted now.
 
Cheers, Rob.