Alex, isn't the key you have there for the 32 bit version of Dim Pro as you've in the Wow 6432 node which is for 32 bit programs on 64 bit OS.

Maybe it's in the other part of the registry for 64 bit programs. Can't check as I'm on a tablet at the moment.

That's what I thought originally , but no the key in #1 definitely works in 64 dimension Pro.
In fact it seems to utilize both keys,
 
HKEY_LOCAL_MACHINE\SOFTWARE\Cakewalk Music Software\dp\
It gets the settings from this as in #1, it takes heed of the multisamples setting for instance.
 
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Cakewalk Music Software\dp
If you change this it will prompt for serial numbers etc, so this isn't redundant, settings are non effective here, it ignores the multisamples setting.
 
It's all a bit weird how they've done this esp when other people have "Dimension Pro" rather than "dp".... Nightmare...
 
I'm beginning to think the only people who can make sense of this are Cakewalk.

I've contacted technical support via webform (first time I've ever done this!)..  Cheers...

I used Sysinternals ProcMon to trace the registry queries for Dimension Pro and found an interesting tidbit.
Just before loading the MultiSamples it asks for the following:
 
HKLM\SOFTWARE\Cakewalk Music Software\dp\Use Single Folder
 
but gets a Name Not Found error in my case.
 
Perhaps if you set this value it may use a single folder for both.
 

Nice detective work, problem is without any documentation anywhere you are stabling in the dark about its use or what parameters to give it. I bet you it's attempting to read that key in error, the code that's being executed seems a total mess in this area at first glance... registry settings all over the place. Of course Rapture will probably be exactly the same.

I put the program files on the C drive, SSD, and support files/banks on the D, i thought.  That's where a lot of overhead exists.

What I'm doing is purely organisational, anyway still nowhere nearer sadly, lots of interesting things cropping up here though.

A while back I posted material about moving stuff like this:
 
http://forum.cakewalk.com/FindPost/2673527

@CakeAlex; I have successfully done this before, a while back on X1 I believe.
You are on the right track...
look in users/appdata/cakewalk/DimPro/ or similar.
If you've been on sonar as long as your post count inplies, you may  find a solution there.
 
peace
 
mel

One quick question....
 
If you move the multi samples folder do older projects still find the sfz files? or is it similar to Kontakt that they still look for the files in the original location?