The Predator X34 is a really good monitor if you're lucky enough to get one without these f**kiing annoying scanlines that appear when FPS drift away from the frequency you set in the OSD.
I tried up to 5 monitors for 2 months and all of them had scanlines (with OC & Gsync ON). Also, I could see them in the desktop at 100hz by moving a plain color box over the screen, though it's less prominent than in 3D.
All X34 I got weren't equally affected by these scanlines and the last one was the better and had no BLB, really good color uniformity and no coil whine.
But at 40-50fps, scanlines were really visible in Witcher 3, for example.
At 3 weeks from the PG348Q launch date, I think it's a better option to wait and see if it's "scanlines free" but honestly, I have doubts about that. Same panel and same Gsync unit.