For anyone interested in using a Shared SSD across more than a single Mac, for your Arturia instruments.. It works. I ended up re-installing V Collection from the two separate systems, in order to get pointers, configurations, licensing, etc happy. There are some niggling issues when you're done, so do this at your own risk. Your mileage may vary. Professional driver on closed course. Yadda yadda... Here is what worked for me...
1. Launch Arturia Software Center on one of the systems. Follow the Arturia directions on moving Arturia resources to a different drive. This video is what worked for me ->
https://www.youtube.com/watch?v=FTik761IMag&feature=emb_logo . When this is done. There should now be an "Arturia" folder on your external SSD. This process will link things up, so that the Arturia V Collection instruments will work from this drive.
2. Rename the newly created Arturia folder on your SSD to something other than Arturia or move the folder to a backup drive somewhere. You do not want the "Arturia" folder on your SSD before the next step, or the process will complain / get stuck.
3. On the other Mac, launch Arturia Software Center and follow the directions for moving Arturia resources to a different drive (same video as above). When prompted for 'where' - point the installer at the same external drive you installed in the first step. This will re-install all the Arturia stuff from the other Mac onto the SSD. It will also link things up, so that the Arturia V Collection instruments will work from this drive.
Done? Well not quite. I found I needed to get out of Arturia Software Center completely.. and relaunch. It prompted me this first time, for my Arturia credentials. Then after verifying everything worked, I plugged my SSD into the other computer and launched Arturia Software Center. Once again, I was prompted for my Arturia credentials. In both cases... it was only the first time after moving / pointing Arturia resources at the external drive, that I was prompted for the credentials.
The good? Patches, Playlists, etc all get moved to your shared SSD. Create or update a patch on one system? When you plug the external drive into the other system - those changes are all there. Groovy.
The bad? Well.. If you launch an Arturia instrument, or Arturia Software Center, or Analog Lab, etc... and DONT have the SSD/External drive plugged into the system, it dies a horrible death. You will get an error saying that the Arturia product you were trying to launch quit unexpectedly. You can Ignore, Report... or Reopen. What you cannot do though, is successfully launch the product. You HAVE to have the SSD/External drive plugged in. Definitely some kinks to work out. I suspect (or hope) Arturia will fix this mess.. and make it easier to install/link from another system, and not error out if you're not connected to the external drive.