Still hoping to work with support on this, know they're busy.
Things I figured out so far
1) I get a error in 1st post when trying to restore disk images created with 7.1
2) Error in first post from dstasks.log mentions GUID 6c2a2be7-cfa2-4d91-8df6-0ea43aaa230d. I don't know if that's supposed to match a GUID (folder name) in my images folder, but it doesn't. The folder this image is stored it starts with e7
3) I get an error when restoring backup images created with 7.1. Error in dstasks is "[2014/01/02 14:40:57.604 1716:716 2] Function:util::CNetShare::DoMapping,File:common\util\NetShare.cpp,Line:124.Using IP -> Z: have failed in mapping to \\cms\Deployment\Task Handler\image\c6be889b-f8eb-4ab2-b766-9f7faef2b183. Windows Error Code is 67"
4) The guid in the error for the backup image matches the folder name where the backup image resides.
5) I can create and restore a new backup image. When restoring a new backing image created with 7.5 it gets the image file from "\\cms\NSCap\bin\Deployment\Packages\Images\guid". When I browse to that location, the only image there is the one I created today.
I'm working now to see if I can create/restore new disk images, but my guess is yes.