However it is only a move up of one (for GTX 460 768MB) or two (1 GB version) levels on the THG hierarchy chart and they recommend not upgrading unless you are moving at least three levels.
Note that the performance of the 768MB version is almost on par with the 1 GB version and, since it has been selling at a much lower price lately, I have been rcommending it over the 1 GB: