I am using two 2560x1440 monitors right now.
They are:
- TN 144Hz freesync (BenQ XL2730Z)
- IPS 59Hz (Random Korean A- panel)
They both have their places.
At first I was quite disappointed in the BenQ, but it just
really needed calibration.
The 144Hz is very nice.
Dragging a window from one screen to the other is a bit jarring, the fluidity of 144Hz must be seen to be understood.
That said, the IPS screen most definitely looks better.
The color reproduction and vividness blow the TN panel away.
Also, the BenQ has an anti-glare coating which hurts the image quality while the IPS has a glossy glass screen.
On to freesync:
I have only played one game since I got the BenQ: GTA 5.
I average 50-80 fps, and the game looks awesome at any of those rates.
There is an occasional dip (happens maybe once every couple of hours of gameplay) to below 40fps (the limit of the BenQ's freesync range), and the difference between 39 and 40 fps is huge.
I plan on buying a 2560x1440 IPS 144Hz monitor whenever they manage to bring the input lag down, and hopefully then I'll have the best of both worlds.
To answer the OP's question: yes, 100% I think 2560x1440 @ lower frame rate is superior to 1920x1080 @ higher frame rate... and that 2560x1440 @ high frame rate is even better