As I said, I was a GTX 460 owner so I remember them well. Cracking cards, apart from the 768MB one which had a narrower bus, slower ram, fewer ROPs and less cache. It was a dog, and all for about £20 savings. I bought my 2GB one with absolutely no evidence that it was faster than the 1GB version, but it lasted half a decade so I was pretty happy with it.
Just stumbled upon something more up to date, Assassins Creed likes 4GB on an R9 380, but it doesn't matter on a GTX 960:
More interestingly, the 4GB 290 is faster than the 8GB 390 (clocks adjusted to be otherwise identical). My take home for that is that this game is probably tuned to be optimal with 4GB of ram at those settings at least on AMD, but not to the extent that it actually matters.
Now this is a really interesting one, as it uses a texture pack that requires 6GB of vram:
Looks pretty good at 4GB to me, and even 2GB looks playable.
In all, none of the games hit a wall at 2GB. If the settings are wound up enough to show a difference, then it is a slideshow regardless of how much vram you have. Back it off, and you are in the noise of measurement.
Have a read, it seems a well done article:
http://www.techspot.com/review/1114-...mparison-test/
I still think that *if* you can afford it the small extra is worth paying for more ram, but it isn't worth getting worried over. I would choose a card with better cooling over one with more ram, that is more likely to make a performance and noise difference.