Disclaimer: I have never owned a 1440p screen nor a >60Hz screen. I just recently started obsessing over them.
Star Brood wrote:... in reality the FPS numbers vary wildly depending on the situation. In the beginning it's well above 60FPS, during mid-game it's about 40, and if there are heavy heavy numbers of units it drops below 20-30FPS.
Disclaimer: the next I confess I have no idea what I'm talking about:
Based one what' you're saying, there are 3 more chances (24, 40 and 60+) for 120Hz to appear better on the screen. Does this not also mean that frames between 24-29 and 40-59 will look better on the 120Hz display?
That's totally correct. Especially with v-sync enabled, you'll probably find a 120+Hz screen looks a little better at low framerates simply because there are more... "harmonics", if you will (120/60/40/30/24/20/15 vs 60/30/20/15). You'll be locked down to the nearest lowest harmonic with v-sync on, as usual. And when you can blow past 60 Hz, you might find having v-sync off to be more bearable since the framerates are so high (sort of akin to disabling/reducing AA on high-dpi screens).
Combine this with the fact that most competitive games don't offer resolution advantages (ie: SC2/LoL/etc will scale the camera zoom and HUD so every player sees a similar viewport), and you have a clear choice, imo. Resolution doesn't do anything for movies really either, until your source and compression ratios can outdo 1080p. And that's a ways off from being mainstream. The main advantage the IPS screen offers--for you--is color accuracy and gamut.
Something else I want to note regarding your original post:
Star Brood wrote:1) Do you notice any peculiarity in video playback? I have seen some TV shows that appear with odd motion on 120Hz TV's. Like, sometimes moving more quickly than they should, and just for moments at a time.
I picked up on this, too. I think it's because some scenes are 60fps-enabled and others are 24-fps enabled. It is very annoying, and I've noticed it more in CG-heavy movies--like when Avatar was playing in Best Buy.