My two biggest wishes for PerfectTunes De-Dup:

1) Formal rules or priority of "copy to keep" to make "Mass Delete" more functional and appetizing:
For example, fine control over rules for "mass delete" including, for example bitrate, codec priority, length, path expressions.
Or, in the alternative guarantee which copy is kept by using the order of the folder list setup to be scanned.

2) Symbolic link option
When a file is deleted, have an option to create a symbolic link in its place back to the kept file.