One of my computers uses a MSI nVidia GTX 750 Ti, the other a EVGA nVidia GT740 graphics card. I have played Obduction 3 times with the 750 and once with the 740. The main difference in performance is in the speed and smoothness of avatar rotation, where the 750 Ti is the clear winner. But the GT 740 suffered from another issue: in underground Hunrath, the paths sometimes show black "puddles" which clear up as they are approached. In general, the better 750 Ti (51 fps on "Heaven") IMHO does meet the "minimum requirements" for Obduction's Mac version, whereas the GT740 does not. Also, although the latest Mac version has solved the crashing problems for the 750 Ti, several crashes occurred during "seed swaps" when using the GT740.
No doubt the higher performing graphics cards such as the 980 - 1080 work even better, but at least (again IMHO) it seems that Obduction will play well even with some lower-performance cards.