I've bought SoC on steam over the holiday sale and started playing it this week with the Complete 2009 mod. I'm having an awesome time (just turned off the brain scorcher), especially compared to when I played it when it launched (didn't even leave the cordon then because of the bugs). Steam is offering a deal for owners of previous games in the series to get it for 20 euros, and this tempts me as I am definitely up for some more S.T.A.L.K.E.R. if it isn't buggy, runs well, and nails the suspenseful atmosphere, especially the horror moments.

So is there anyone who played SoC with the Complete 2009 mod that thought this was a good purchase?

Yes! It is the best vanilla STALKER game yet, by far. It doesn't look as good and isn't quite as polished as Complete 2009, but it's about a thousand times more polished than the first two Stalker games. Very VERY few crashes at all, though I've been running into them more often, the more I mod the game and load up a bunch of different saves in one sitting.
 
In fact you can use many of the Complete 2009 textures in CoP to help bridge the gap. Combined with the Atmosfear mod, CoP looks excellent and runs better than any Stalker before.

Yup, modded the hell out of SoC. 
 
CoP is by far the best Stalker so far.

BUY IT!

I've only played an hour or two of it so far, but it's easily better than the first game. Runs surprisingly well on my 8800 GTS too, I was expecting to play on medium settings. 

I kind of miss all my old mods from the first game though. 

Hmm maybe I should give the first STALKER a whirl with mods. I didn't give the game a chance because I was hung up over the bugs and archaic presentation.