8192. I would suggest disabling AA in the options menu and not using AF in the config file, seeing how it works at 8K, then gradually adding AA back in. I've seen reports from people saying it works fine with 1GB and other saying that it doesn't, so it's totally hit and miss at 1GB.
Also, I updated our story with some Transcoding tweaks that until now were a tad mysterious: http://www.geforce.com/News/articles/how-to-unlock-rages-high-resolution-textures-with-a-few-simple-tweaks
Well I ended up trying it just as is and to my surprise even with 2x AA it seems to run just fine. Textures are better and less pop-ins too. I have just a Palit GTS 250 1GB Green edition OCed a bit, but it seems to handle this game beautifully. I imagine one of the reasons it's not a problem is I only run 1280x960 since I just have a 22" (20" viewable) Dell CRT display.
On the GPU Transcoding tweaks, I did read about those too but it seems it's only recommended if you're experiencing texture streaming problems if I'm not mistaken?
Thanks for your help Andy, you guys at Nvidia always put so much care into how well games run on your product, and others as well. You deserve praise for it.
Oh, one last question before I forget. My neighbor has a GPU similar to mine but with only 512MB VRAM and he runs a 1280x720 res. Can he make any use of this tweak if he lowers the image size a bit, or is it even possible to lower it from the 8192 value without it looking the same as the default textures? From what I recall values pertaining to memory usage can only be halved or doubled, so I'm doubting it.