Hello AoXoMoXoA,
I haven't used the "Incomplete Albums" search yet, but the new tag (let's call it "Featured Albums") I'm trying to create could be used in another revised "Complete Album" tag, which considers "Featured Albums". I think the problem could be solved that way.
To play a complete album won't be a problem as the information resides in "Featured Albums" and can easily be searched.
Getting to your last points, I do not consider live, remixed or extended versions as duplicates because they are considerably different from the originals. The file format is of minor interest to me as I mostly use MP3 because my ermm...MP3 sticks ? (I'm not sure you can still call em that with how versatile they've become) only recognizes WMA and MP3. I kinda neglect WMA so MP3's my choice. If you aren't bound to your MP3 stick then I suggest you choose the file format by a certain criteria e.g size, quality, ratio quality/size, etc.
Although my net storage isn't small (1TB) my MP3 is (2GB) and duplicates are annoying. Adding to that I'd just like to keep a clean library, meaning correctly tagged, minimum size, acceptable size considering the number of songs, lyrics, .... Saving track information twice could gradually fill the music partition and I don't wanna get into the situation, which forces me to delete dupes and "mess up" my library.