1/ The interest of the Polaris, compared to the Memovox :
I think you speak of the Amvox I ?
If this is the case, the answer is easy: The Amvox I is the Hommage to the Polaris, and nothing can beat a re edition, even if some things are very close between these 2 watches.
If you speak of the Memovox Compressor, it was presented as the daughter of the Polaris, borrowing some elements to the Polaris, but being a very different watch, IMO.
If you speak of the Memovox Vintage E 855 Black Dial, here again , you have an urban watch ( the 855 ), and a Diver watch...Some elements are common, here, but a lot of differences between these 2 watches...
2/ The Justification to add another piece for the Sake of Hikstory is as good as adding another Perpetual Calendar to your collection...LOLOLOL
The Justification is the Passion, my friend...
And I'm sue you know what I'm talking about!
Best, My very good friend!
Nicolas