I did the same thing only swapped out the Sammy 4k. Found the Swift matches the 4k ones for TN picture quality if not slightly better but certainly not worse. Lower input lag and faster refresh update even when at lower fps. Way superior response times at 60hz as the 4k TN's are not the fastest that's for sure. Thinner and nicer design bezel. Can overclock games to 144hz mode with a press of a button even if they are locked at 30fps or 60fps so you are not stuck with 60hz update, makes judder less on badly made games that g-sync won't help with. ULMB mode for easy to run games with locks at 85, 100, 120 hz, it also has no double imaging as long as you can match the desired hz with the same fps with v-sync at all times, works great and can achieve 120cdm2 still. 4k needs sli or x3 sli to max brand new games without AA sometimes for 60fps which is fine but i found running maxed games at 1440p with triple digit fps much smoother and nicer. 4k is not great when sli is not supported like dead rising 3. On that game 1 titan black OC'd sometimes ran sub 30fps, er no thanks.
I could only see the extra detail sometimes when sat forward, from 2 ft back 4k without AA compared to 1440p with injector SMAA on ultra looked fairly similar in the main so as i don't play games really close i found the 4k not worth it at this size of screen. For AA at 1440p i use RadeonPro, the free download. The SMAA injector works with nvidia, just add a game, select ultra and then select custom which copies ultra to custom (you need to do this for nvidia to keep the ultra settings). This AA works with 64bit exe games as well and is perfect, no blurring of the image and not heavy on gpu power.
This is my experience with my rig comprising x3 titan black. 4k is very nice and all but i found 1440p to still look very sharp when not sticking my nose to the screen and from normal viewing found the jump to 4k less impactful than the jump from 1080p to 1440p which is very obvious even at my seating distance. All this depends on your eyesight and viewing distance of course, types of games played etc. I had the swift and 4k side by side feeding the same games via 2 pc's and made my choice (as said before 4k no AA and 1440p, ultra SMAA injection). Only time 4k showed it's superiority was at closer range, so for me the swift won out with similar image and higher hz via my sli'd setup. Of course g-sync is a must for me now, just let my gpu's run wild on any game and get whatever wildly varying fps on different scenes with no issue of judder or tearing and super low input lag. Playing alien isolation in triple digits with almost no motion blur beats the hell out of 60fps blur and average response times. 60hz control feels so horrible now as well. G-sync has less input lag than triple buffered v-sync when not hitting your max fps. I frame cap my games at 135-140fps to avoid this via the program you get with MSI afterburner for my overclocking.
Hope this gives you a few idea's to think over. I have no regrets over the change unless i sat any closer where i know 4k would look better, but the swift has many other things to sway me even then. I found SMAA injection a must though to mantain clarity and remove most jaggies at 1440p, luckily it seems to work with every game.
