Marciano:
I am not sure how rare they are, really, since there is no attention paid to them until now. There are a ton of European, Asian and South American cards with five or fewer known examples. Some of them are truly rare, some just have not been catalogued until recently. The latter will pour out of the woodworks when people realize they can make money on them. I think it is too early to handicap the Fickjournalen cards. Give it a few years and see how many come to market. The Rover Marciano has been around for a few years now.
I've seen maybe 3-4 of them. I suspect the Ficks are in the same boat but we need to see.
I used to think the Rekord cards were tough until the floodgates opened.