Paradigm Shifter, your review was very impressive in scope and much appreciated. Seeing how quickly VRAM was gobbled up even at 1920 was something that large review sites have not really expressed. You've created quite the interesting problem for me.
The good news is I've made a few decisions since this thread started. While there was plenty of positive feedback that 1920x1080 could be handled with ease, I ended up with 5040x1050. Just landed a solid deal that made the decision easy. Your data in combination with everything else I saw kept me away from 5760x1200. Playable, but not what I'm looking for.
On the card side, 2gb seems like a slam dunk for a few bucks more. However I got in on the Asus GTX 460 1gb Top (775 stock clock) preorder for $210. The only 2gb card available in the US is the Palit, for $270 shipped. Thats one helluva jump in price. Plus, in the US, Asus is an established market leader with a clearly high end product. Palit is neither. I'm leaning towards sticking with the Asus cards, and trying out the Sparkle 2gb cards if/when they're released (lifetime warranty) if I find myself running into a VRAM wall too often.
I'm usually focused on maintaining the highest min framerate I can though, I rarely use AA at the moment. That will limit VRAM usage somewhat, and there will certainly be a difference from the 5MP resolution and the 7MP you're testing at.
Oh, the only other direct information on 1gb vs 2gb I've found for anyone interested:
http://en.expreview.com/2010/08/08/exclusive-review-of-zotac-geforce-gtx-460-2gb-edition/9041.html/9 The highest resolution they benchmark to is 2560, unfortunately.
Again, thanks for the tremendous amount of work you put into the review Paradigm Shifter!