im thinking similar thoughts, whether its wortth trying on my imac 3.21ghz with 1 gb 6970m card. i saw one framerate comparison of different cards which did include a 1gb card, the results werent great but definitely acceptable. i played 3 and nV on a mac mini 2009 so im accepting of a bit of slowdown and low quality graphics to play a game with a great story.
Working from road this week and running it on my "old" 2012 Macbook Pro w/Retina (i7, 650m). 1650x900 with most settings to low (textures on high) with a few necessary tweaks (Nvidia v-sync overriding Bethesda engine - big FPS gains, caping FPS to 30 FPS, etc.). Very fluid and no stuttering.