Okay, but in your MC library how are the filenames/paths stored? I want mine stored as (in your example) E:\Music, not \\mediaserver\music. That I cannot do. MC wants to copy to E:\Music if I change the filenames from \\mediaserver\music, and then it can't because it finds the files already there...
In my setup I want to have two computers with mirrored copies of my media, \\comp1\M:\music and comp2\Q:\music. I want each computer to have a junction to \\comp1\C:\music and \\comp2\C:\music, and I want MC's library to find the files on the C: drive in each case. This would let me maintain mirror copies of my media and playback from each local machine rather than across my network. If someone in my living room trashes my install on comp2 or deletes something, my comp1 is unaffected. I currently let guests stream from my comp2 while only I stream from comp1. By using the junctions media is always referenced from a drive C: regardless of how I might change/add/merge physical disks on either machine in nonsymmetrical ways. Even my MC library is located on the two drives and remains identical and up to date across machines (so long as I sync from comp1 to comp2 when I make changes). To synchronize the two machines I use an external program (Vice Versa Pro) to sync from comp1 C: to comp2 C:.