Most non hardcore gamers will not notice the difference between 900p and 1080p.
I myself have trouble telling a 30fps game from 60fps, and cant really tell a difference between 900/1080 though screen tearing is obvious.
Also, bigger res. differences like 720-1080 are a lot more obvious...when playing titanfall, I noticed that it did not look near as good as some of the other games I had played such as F5, or Ac4.