I've owned multiple Shiros and all of them had better action than the Hinderers I've handled (though I haven't handled the latest generation, so who knows).
That said, I've handled plenty of other knives that had similar action to the Shirogorovs I've owned. Beyond a point there is no way to improve; if it hammers open and falls shut there's no place left to improve and there are a lot of knives that get there nowadays. The days of only Shiro/Thorburn/etc. getting there are long gone; I've got some cheap CRKT folders running on IKBS that get there and CRKT isn't exactly known for being a paragon of manufacturing excellence.
I'm not even a fan of the absolute free fall on close, though some of knives I carry and like (e.g. Seraphim Korsar, Jason Clark custom, CKF Milk, etc.) do operate that way. I think my happy place is "snaps open but takes a wiggle or two to close". Free fall on big blades like the Korsar, the JC and the Milk has never bit me but I've surprised myself a few times closing them one handed when my usual motion ends up with the blade falling closed a step before I expect it. I've almost tagged my thumb that way with all three of those knives, as my thumb is pulling away from the lockbar and my index is lifting the blade as normal it just flies up and over because it's so smooth and down comes the blade. No big deal on a thin little 3" blade, but the weight of a thicker 4" blade brings it down quick.
I look at "perfect action" as being like a mirror polished edge, something that's neat to have/do just to see it, but after the novelty wears off it's counterproductive. Polishing edges through ten progressively finer grits because you enjoy doing it is fine, but a polished edges always seem to lose cutting performances faster than a gritty edge does. Similarly, a knife that takes a wiggle to close will never try to take a bite out of my right thumb.