I have some Fjallraven Keb Trousers, which look pretty similar to the Vidda. They're extremely versatile- I've used them for work, general wear, hunting, scouting.... prettymuch everything. My only complaints are that the wax application does almost nothing for water resistance compared to a high quality DWR garment... like it was so disappointing after two applications of it that I just quit doing it because 1) it's a pain in the ass, and 2) anything more than a little misting from a sprinkler overspray or dew still soaks right in.
They also don't believe in back pockets. I don't care about that for hunting because my pack makes back pockets harder to use, therefor I tend not to use them. But, for work and everyday use outside of hunting, I find myself searching for them.
I love the knee pad pockets and vents. Love the fit/durability- I'm really hard on stuff, and they've held up really well.
DWR wears off after a few hard hunts and bloody washes, and then is useless unless you reapply. Fjallraven waxing works and is easy if you know what you’re doing.
My heavily used Acrteryx DWR pieces require reapplication of DWR after about 10 days of hard use.
Fjallraven pants work very well. Vidda pro ventilated and Keb Agile for hot/cool hunts. Keb and Vidda Pro for cold hunts are all I use these days.
I think keb and vidda pro are very different. Vidda pro has flex in crotch gusset but nowhere else. They are the most durable pants I have had, not as good as filson chaps but really good. I don't own keb but have tried them on multiple times. Much more flexible and comfortable, but no way they would hold up to the small game hunting I was looking to use them for. No experience with born primitive pants.