Right now I have a Perrin FB, but for me the grip is a tad too small, and as a result feels slightly insecure...
... I have medium sized hands, and my fingers are fairly long
Seems I understand what you are talking about. The same complaint from my side. Perrin handle is excellent for the grip suitable for some kind of knife-fencing. However for heavy cutting in hammer grip I would like forefinger choil to be at least 5 mm shallower.
Fällknivens have more conventional grip, they are less risky to buy without pre-handling.
F1 vs. FB Temperance, hmm... Temperance has more complex, I would dare to say more ergonomic handle and as result more comfortable grip. On the other hand if it wouldnt match your hand the ergonomics turns to you with its opposite side, in this case F1 simpler handle could serve you better. Some comparison try to handle a mach-grade sport pistol with the handle highly tuned to someone elses hand what doesnt match your palm and for comparison a handle of a broom. What would be more comfortable to handle?
Of course it is way exaggerated, with the knives is not so tragic, I just used this to illustrate what I have in my mind.
Additionally Fällkniven handles are made of checkered Thermoun Elastomer what is somewhat less slippery than Temperance handle made of FRN (Fiber Reinforced Resin).
IMO you definitely should handle both before buying. Or to take a risk and buy the knife you like better in absentia
Fällkniven black teflon coating provides non-glare surface and high rust resistance. On the other hand it is prone to get scratches and the knife blade on heavy use becomes pretty ugly. In fact if you are not going to use your knife in very aggressive environment you can go with satin finish without any problems. VG-10 stainless steel is enough rust resistant for normal conditions.
WM-1 is great little knife, a small bit too big for comfortable and discreet carry around the neck in urban environment but just right for open neck carry going outdoors. Very sturdy blade, IMO it could be somewhat thinner, say 3 mm I could consider as more than enough for its size.
I would advise to handle it before buying also. If Perrin handle seems too thin for you the WM-1 handle might be also.