Migrate B2D Target / Change drive letters

So just to provide an update on this project and in case anyone else is looking to accomplish the same operation - in short, it didn't work as anticipated, so save yourself the time.

I went through these steps:
--Shutting down BE services;
--Creating the additional volumes (partitions) in Windows
--Xcopying all data over from the current volumes to the new volumes
--Changing the drive letter on the existing B2D targets to free up the drive letters that are known by BE
--Set the new volumes to the same drive letters known by BE
--Fired up BE services and BE GUI

(When Xcopying, it helped to use the Exclude switch in xcopy to filter out copying of [recycle bin] and [system volume information] folders - the first volume I xcopied failed on system volume information folder and hosed up the permissions on the root of the volume which had to be fixed manually.  In the end none of this made any difference as I ended up having to blow the partitions away completely from within Windows storage manager and recreate the partitions before the BE storage configuration wizard would even see the new volumes for addition to the storage resources.)

Afte all that, BE recognized the changed drive letters and kept right on going as if nothing had happened.  The properties page of the existing B2D volumes reflected the new drive letters, so BE is smarter than I thought.  In retrospect, the XML file in the BEControl folder of the B2D target volume keeps a thumbprint / guid of the volume for reference purposes which is probably how it found the volumes despite the drive letter changes.  Xcopying the data to the new volumes without making the old volumes unavailable before firing up BE again didn't cause BE to see the new volumes as it's B2D targets.  I didn't want to make those previous B2D targets immediately unavialable in case the operation failed for some reason as I had current backup sets on those volumes.
In fact, it ended up confusing BE a little bit that multiple volumes had the same guid as when I attempted to add the new volumes to storage resources, the configure storage wizard was displaying incorrect data about the volumes that were avialable and even included some (but ont all) of the voumes that were existing B2D targets as if I could re-add them as new B2D targets.
After that, the configure storage wizard couldn't see the new volumes at all, even after re-formatting them to wipe out what I had xcopied over from the existing volumes it was if they didn't exist even though I could see and browse them using Windows explorer.

So, back to square one:  I shut down BE services again, deleted and recreated the entire partition on each of the new volumes so that Windows had a fresh GUID on each of them, assigned drive letters, fired up BE services and the GUI and immediately ran the Configure Storage Wizard.  This time it saw the new volumes and I just went through setting them up from scratch.
Then I had to adjust all of my backup jobs to point to the new B2D target(s) - which was the singular step I was trying to avoid by way of this operation.  Set the to-be-retired B2D volumes as offline in the BE GUI and waited to see that backups would target the new volumes correctly - which they did.

So, long story short - just add new storage targets from scratch and retire the old ones manually.  If I had made the old volumes unavailable before firing up the BE services again, BE might have recognized the new volumes, however I would have a concern about how BE might react to the the volume size suddenly changing, whether or not that would cause additional problems.

Thanks again Craig, Colin for the feedback and suggestions.  Hope this experience helps someone else avoid wasting time and effort.