Same. 144hz is just night and day. There will never be going back. Big reason Im waiting for 4k is to get the 144hz, which we'll have to wait for DP3x for that. Isnt it amazing after all these years, you finally go get a good monitor and wonder why you never had one before. Its like having all the power of a maclaren f1, with the chassis and body of a rusted ford pinto. The monitor is the one thing that displays everything else your computer does. Makes sense for it to be the best. Now come on 4k at 144+!
This is probably the best statement on the matter.
When I did my new build, I was content on keeping my existing monitors (two 1080p @ 60hz) because I really hadn't done much research into any of the 1440p / 144hz monitors. I was one of the ones holding out for something at 4K. I was even going so far as to argue with those telling me 4K made no sense for gaming. It was because I really didn't know the difference 144hz would make. Until I tried it myself.
It truly is like doing a dis-service to a decent setup to still be running something at 60hz. Even if it's only still 1080p, making the jump to 144hz is one of the biggest improvements one can get and the 1080p / 144hz monitors aren't all that expensive. A GTX 970 can handle 1080p @ 144hz pretty easily, and if the monitor supports G-Sync or FreeSync, it would help even more if the PC is struggling a bit to keep up.
We are still a good ways away from true 4K gaming over 60hz. We might see 4K at 100hz by the end of the year, but it's going to be at an extreme premium to get that. Along with that, we'll end up getting improvements to the 2K experience at levels such as 200hz and beyond before 4K catches up.