I use a 960, and I run it at max graphics. the extra 80pounds wouldn't do anything for your experience.
If you were to use that machine to run another game, like say Fallout 4 or something even newer then it would be affected, but not with Elite Dangerous.
You can easily run Elite Dangerous on Ultra settings using a GTX 560, as I did that when I first got it.
Must be something strange with my setup. Fallout 4 runs fine at 2560x1600, high on pretty much everything, yet Elite struggles near planets. I have a GTX690, so I'm guessing it is an issue with Elite needing more than 2GB Ram, and not having any good way of coping with less without stuttering.