The FFG is less common, but, Kizer, WE, Reate, Stedemon, Koenig, and Maxace all combine to have a relatively substantial catalog of $100-$500 knives that have astounding action and construction quality.
There are also a slew of mid-techs by G&G Hawk, Brian Tighe, and many more that are in that same sub-$500 price range that I imagine fall into the same general quality category.
If build quality is the primary metric you are measuring by, Shiros don’t have construction quality that justifies a $500+ price difference over what might be considered competition. Their prices fall well beyond the point of diminishing returns if you’re not also just in love with their designs, style, and brand.
Comeuppance
has already described, I don't think there is anything particularly unique about the action or fit and finish found on Shirogorov knives. It's pretty easy to find flippers that reach max flip-ability (i.e. that you can't make open partially with the flipper even if you try), the same is true for finding knives that run on bearings that fall shut under their own weight. More baffling to me is getting a knife on washers that falls shut even with the pivot cranked down, my recent experience with a ZT 0850--it's bizarrely smooth, it casually middle finger flicks and falls shuts, as if it was on bearings.
