Well, seems like nobody interested in sharing their experiences
I will add mine though in case somebody is looking this up. I have just received the WLF FN, the standard version (not the 6x). I is meant for general photography, does have magnification (reportedly 4.6x so I'll take that number). Here is the first huge difference between this and AE finder. Brightness improves significantly. Not a surprise as there is only one-element loupe on top of focusing screen vs. prism path in AE finder. So the view is very bright and certainly makes things a lot easier to focus and compose, will prove advantageous in low light or with darker lenses. It is light and quite functional. Prices are all over the place, but it appears anything under $100 is as good as it gets right now, barring package purchase with camera etc. where it might be more economical.
I don't have any instructions for it, so am I bit puzzled by two things.
Finder is stored in down position, without raising it will not focus correctly. So one needs to twist it right, raise it, then twist back left to lock in place. Secure arrangement, but why this is not a rigid tube I don't know. Possibly to have it not project to the skies as much when not in use and lessen opportunities to knock it sidewise?
Second is the loupe itself. It has flip down function (that's what the small knob is for). Can't think of a single reason for it outside of teasing the user of the magnification loupe provides. It will not flip down when finder tube is in stowed position, in fact it will touch focusing screen and could damage it. If anyone knows what this is for I'd be interested to know as it appears there was an idea but never materialized in production.
Loupe itself has a top cap, nice to have it there but when pushed in to secure it, it also pushes down the loupe (and holds there in half-ass angle until cap is off). Cannot believe this is the reason why the loupe flips, but for cap it has to.
Eventually I will go after the 6x version, which is much more complicated optical design, much heavier, and for close up work/critical fine focusing. And unlike the standard WLF FN, it also has diopter adjustment.