In case anyone is on the fence about buying FC2 because of its respawning enemies, here is an actual mod that alleviates that problem a little.

http://www.moddb.com/mods/far-cry-2-rewards/downloads/far-cry-2-rewards-mod-10

And here is a mod that makes the game look quite a bit better, and less...muddy. You must run the game as administrator in WIn 7 64 for this one to work.

http://www.moddb.com/mods/far-cry-2-graphical-enhancement-suite/downloads/fc2-ges-v1001

New on the block: http://www.moddb.com/mods/dylans-far-cry-2-realism-mod

It's another weapon damage/AI detection adjusting mod, claims to be "realistic."

Apparently Far Cry 2 was developed with an open hostility to any kind of meaningful modding, damn shame.

Using the realism and the enhanced environment mods. Slight increase in difficulty (I'm used to russian STALKER mods), better handling on guns.

I agree with the above post. I am considering doing my own mod for extra difficulty and more stealth emphasis.

Is there a version that works with GOG's release?

Use the fortune's edition version, it worked for me without issues.