UniversalWolf: I successfully installed L.U.R.K. 1.1 on the GoG.com version of SoC, so I can confirm it works.
As for the mod itself, it's a mixed bag so far, with some things I really, really like, and some things I really, really don't like.
Positives It has a nice look, with higher res textures and a darker, browner, more sickly looking landscape overall. A little too much bloom and blur for my taste, but I suspect this can be adjusted. The new UI graphics are snazzy.
It has more kinds of guns and ammo, including the AK-47 (and variants) and its 7.62x39mm ammo which were conspicuously absent from the original game. Also, SKS rifles...yes please.
Med kits and bandages take a small amount of time to use. I quite like this change, even though it can be damned inconvenient at times.
I haven't tested the stealth system much yet, but there was plenty of room for improvement from vanilla, so I'm hopeful.
Negatives Carrying capacity lowered (yes, lowered) to 40.0. Just silly small, and not convenient or fun at all. If you have a couple of sawed-off shotguns and half a dozen pistols in your backpack, you are immobilized. This should be completely left to player preference, IMO.
All HUD removed, except for the compass and reticle. There is no mini-map. There is no health meter, no fatigue meter. Losing health and energy instead makes blood splotches and what looks like oil stains cloud your vision. I gave this system a fair shot, and I'm not a fan. Again, this should be left to player preference, but as of LURK 1.1, it is not.
If you're of the "harder and less convenient is more fun" school, you might like L.U.R.K. As it is, I like some things about it, but I can't see myself playing through the whole game with it until some of its "features" are selectable.
This is why I consider a nice front end or even a .ini file that lets you enable/disable certain features to be a necessity for any serious partial conversion or "fixit" mod.