So far my experience has been "flawless" with FreeSync. It has been a "buttery" smooth experience like I'd read from others posts in the past.
I don't usually buy the latest games, just because I like to get them when on promo, so will try some older titles. I do have Assassin's Creed 1, tend to use the DX10 exe but will try the DX9. I've yet to play it on the MG279Q with FreeS ync in either mode. I know on the Eizo 1080P@120Hz there was this odd hitching , this occured with my Hawaii & Fiji card, but I can't recall it on my HD5850 when used on 1080P plasma and an older Samsung 1680x1050 monitor. AC1 though at 1440P@60Hz on the Dell U2515H with Fiji was sweet, no hitching, hoping it is the same experience on MG279Q but be able to use FreeSync or 120Hz+.
I also have Lost Planet 1, I know with what cards/screens I tried it on in the past I had no issues, regardless of DX9 or 10 exe used. Yet to play it on the MG279Q, if an issue with FreeSync will post.
I know some monitors have had firmware issues, dunno if yours are one of them. I know early MG279Q did, mine has a April 16 manufactured date, working great, even the OverDrive option in OSD (called Trace Free).
Mine is an open box purchase from Amazon Warehouse. It was £355, cosmetically like new, still had spec stickers on base/screen like no one used it. Whilst testing it I found minimal back light bleed. Less than the Dell U2515H, it is so much less that I can use a background with all black screen (apart from graphic in center) on the MG279Q. Screen uniformity again seems great to eye. I found this odd bright patch on screen whilst testing with single color full screen fills. The pixels change with color. So not stuck or dead, the patch is 1mm sq, more apparent on bright deep single colour fill screens and virtually non existent on light color or black fill screen, located about 2cm above the S on Asus logo bottom bezel. It does not a) come in the FOV at all in normal use b) as it changes in color you don't note in games/os. I gained a further 20% discount. Paying ~£280, the patch in brightness seems to be diminishing as I use the screen more, so it may disappear but if it doesn't truly no biggie, considering screens normal price is £460-£500. This 1mm sq bright patch is my only issue with the screen so far.Edited by gupsterg - 10/6/16 at 1:26am