I first played STALKER at the 1.0003 patch level, good game but buggy.
About 3 months ago I stumbled onto the OL mod and decided to revisit STALKER. During that gameplay, I then discovered Priboi Story. Both fine and enjoyable mods to STALKER SoC, thanks so very much to the authors Kanyhalos and dez0wave - and ALL the other modders who have taken STALKER to a new level.
Played both, then started looking for another, SIMBION seems nowhere to be found but I grabbed NEWSA+Simbion. Though a bit concerned it wouldn't play, it's been enjoyable so far!
My concern? System specs of a mobile Athlon OC'd to 2.2 Ghz, 1 gig ram, Radeon 9600 all on a DFI NF2 motherboard. Tweaked pretty heavily as I used to O/C for a hobby, but still far below Nightwatch's minimum! Graphics settings on medium, static lighting, full screen at 1024x768 on a 1400x900 monitor looks OK, not exactly eye candy but playable.
Well, Cordon played nicely, as did Garbage. Dark Valley was a bit of trouble as my inventory pictures scrambled. But it unscrambled after coming I sold a pseudogiant brain to Barkeep. Lot's of surprises in DV!!! Gameplay was smooth, NPC's all were quite aggressive.
Bar plays well, but wow! It can sure be a hellhole with exo Mercs or Soldiers invading from AW and Bandits from Garbage at the same time. Plenty of fun for everyone! Though my framerate drops into the 10's during that kind of action.
Army Warehouses really put a slam on the game and my system. I almost gave up. Framerates were often less than 1!! The script engine couldn't keep up with my movements, so NPC were often in a pseudo-zombie state. It took 2 real days of gameplay to coax an end to the errant Dutyers (thankfully a blowout took them out!) before the level was even marginally playable! It still has low framerates and stuttering but I did the snitch mission from Lukash in one go.
Something happened between AW and Cordon, Syd only does two things now: trades and tells me to hide, he won't buy any Army from me. So, two jobs Syd assigned will Fail because there's no "I'm here for the job" dialogue. It hasn't seriously affected the gaming but like Nightwatch has said, you need a decent rig to play this mod.
Wild Territory and Yantar played about as smooth as vanilla, the only hitch was having to reload multiple times to get a spawn that didn't have a whirligig directly in Krugolov's path. Met my first Dark Stalker there, sorry to see him lying dead on a second visit

I'm now back at bar after turning off the brainscorcher. Imagine my surprise to find Duty base almost intact but the whole of the rest of the Bar was occupied by Army! 20 or so to be killed before it quieted down, but as soon as Army was wiped out Bandits thought it was prime picking, so almost out of ammo, I had to help Duty with a raid. Arnie is dead, so no more Arena action. Only Snitch, Baldy and Barkeep are still alive. Sevka Goblin also bought the farm. I was a bit shocked at that since he was listed #1 Stalker in ranking, plus I'd given him a medkit once so he was my only Duty friend. Blasted military!
I have doubts I'll be able to finish the game, it sounds like Stancia will kill my system if Prypiat doesn't. I'll be finding out soon enough.
Anyway, many thanks to Nightwatch and all the other contributors to NEWSA+Simbion. Great fun!