I would advise you to test all scenarios and see what your performance is like if you can get away with only having one copy of images for all your clients that is always a win and if you need to keep them all locally because performance isn't good enough you can go that route also. By the way I'm impressed with your dual Xeon 192 GB of RAM setup there, its terribly overpowered for a home machine but still impressive. That's the kind of system they install like 25 VM's on and put it in the server Room