I have read that many people think it isn't necessary, and that the FRN is sort of "self lubricating". Still, I find them smoother with a bit of occasional oil, especially after rinsing them out. I use Ballistol. It works great, and keeps them food safe.
Age old answer...both of course. It is the right answer. Seriously though, I currently have neither. But I do have a Salt and a Pac Salt. I carry the Salt more, but if I had to have only one, it would be the Pac Salt. No help, I realize. Get both!
Not long-winded, I enjoyed reading it, and love your Military collection. I had one long ago, and found it too big at the time. I really don't think I would feel that way anymore at all. I should definitely try again someday.