So the question remains ... or at least I'm not clear yet ...
 
Is there a problem with the Platinum (/Foxboro) installer that removes or does not deploy necessary SonitusFX .ini files?
 
(necessary in the respect that the presets were once included and should continue to be included).

Yes, the Sonitus *.ini files are now in the Shared Plugins folder. I reinstalled Sonitus from X2 (not Platinum) and the files turned up. They were useable in Sonitus plugins in X2 but not Platinum since they live in a version-specific registry key. Then I rolled back to Everett and re-installed Foxboro, and now Platinum is seeing the presets too.
 
I don't have a good theory as to what went wrong, but suspect a problem with the Foxboro installation (although it would have to delete existing registry keys pointing to the presets to cause this). Anyway, good to go (although I lost half a recording session).
 
Cheers, Peter.
 

Peter ... Good on you for resolving your issue.
 
... But ... I'm also thinking about 'the next guy' (maybe me) ... who a. doesn't recognize or b. Installs anew, doesn't get the presets and thinks situation normal.
 
Without 1000 people in the forum checking/responding, although a few may be helpful, it should be easy for Cakewalk to confirm whether the .ini files are still required (I suggest so, in the case that the Reg entries are removed or were never there) and that they are still distributed with the installers.
 
I'm going to follow progress ... and raise it in the Feedback forum if a definitive response does not come out of this thread.

Make sure you raise it in the feedback forum. The Bakers monitor that closely. This forum is considered more peer-to-peer.

Thanks Craig - will do.

Raised to the Feedback Forum:
http://forum.cakewalk.com...ler-sets-m3248699.aspx