There was a time when I had Project 5, DimPro (purchased as an upgrade to Dimension) and DimLE (came with a version of SONAR) installed on an XP machine. Each version of Dimension has a different ID and shows up as a different synth. That is why the chains in P5 do not recognize anything but the original Dimension. You can always run a SONAR installer in advanced install mode (it is one of the first screens in the installer). The advanced mode will offer an option to select what to install. I have never seen the X1 Studio/Essentials installer or packaging. I know that the X1 Producer uses a separate installer for DimPro, Producer does not include DimLE. The installer is located in the link for X1 on my store account page. Does X1 Studio/Essentials have a download layout like that? If so, you would not use the SONAR installer to install DinmLE, there would be a separate exe to install DimLE. Either way, that is why there is no link to download DimLE on the line with the registration credentials.

I didn't think dxi would work on anything past Win XP, thought it was the last version they did work?

No, DXi still works. All plug-ins and the synths above the ---- line in the SONAR X series browser are DXi. The issue with DXi is 32/64bit. With the exceptions noted above DXi plug-ins are 32bit only. The 32bit plug-ins will not work out of the box on 64bit SONAR but will work in 32bit SONAR running on 64bit Windows. In order to use the 32bit DXi in 64bit SONAR they need to be wrapped as VST the loaded into a bridge. But that is a topic for another thread.

Curiouser and curiouser.

I installed the Dim_VST from my X1 package. Fired up Sonar, added a DimLE and sure enough there was V1.5 with the Garritan Pocket Orch, etc. So, I quit and started P5. It found its Dim_DXI without the Pocket Orch etc (ie its own pool of programs). However, now when starting the VST for Dim_LE I get the P5 version only. The Dim_LE_VST_V1.5 seems to have disappeared and only DXI version (with an XXXXXX) version number is available from Sonar, other hosts and standalone. 

Now to see if Dim_Pro will play nicely.

After a re-boot, things appear to be OK. I can now load Dim_LE_DXI into P5 and Dim_LE_VST_V1.5. I also got Dim_Pro installed. But now, I can't install the 'DSF E-MU Proteus Pack' into D_Pro. It installed into the D_LE just fine. I did the install of the DSF file, start Dim_Pro, F5'ed the browser, but the E-MU files don't show up. They do show up in the D_Pro programs directory. Oddly, they are the only files showing up in that directory. None of the dirs or progs shown in the browser are located there and I can't find the browser programs anywhere. All of the MultiSamples are where they belong. 

Any suggestions on how to get them to show up in the browser? 

OK. I found the Program Data/Cakewalk/D_Pro/Programs folder after searching the boards here, copied the files over, F5f'ed, and now they're showing up. Not intuitive, but progress.

Yes, it is useful to know the file layout for DimPro (and Rapture). Depending on the vintage of the package installer and your config, slinging files around is not uncommon.