Pia, I just did as you asked. In the end, I had to set quality settings to LOW to maintain an average of 100FPS. I still saw no difference in overall movement or smoothness. And to achieve that framerate, I had to drop Textures, Level of Detail, Shadow Quality to low, turned Anti-Aliasing and Anisotrophic filter to the lowest settings. If I lower the resolution, I could probably get it to average 120FPS, but That ain't going to happen. Running non-native resolutions just looks horrible.
I tried these settings, again, both on the IPS panel at 60hz, and the 120hz panel, and motion appeared identical to me.
So, I gained jaggies, and lost detail to get more FPS that gave no visual improvement to smoothness. I have to give up too much to gain a so called benefit I can't see. Yes, it's subjective, but it's what I see when I play. At least I can say, I am actually doing a comparison.
ieatdonuts, that's your call. you clearly place your priority for a percieved benefit that can't really be demonstrated over general visual quality. More power to you. But, I am also a gamer, and I will never buy another TN panel.
It sounds like the original poster is also expecting improvements day to day usage, and even asked how much better 120hz is for dragging windows and scrolling. The answer to that is, of course, It's not, and for general computer use, an IPS panel is far better.
Now, if he is going from a 60hz TN panel to a 120hz TN panel, He will absolutely have a better experience than his old display, but for the kind of money a 120hz TN panel costs, I still say IPS is the way to go.
Almost universally, those that go IPS say they will never go back.