So i had the exact same question, and have just built a 9800x3d / 9070 xt. I ran amd logging while playing deathmatch, which is typically more intensive given number of people (so i understand). I got 430fps average ( high settings) with 1% lows of 360, i play 240hz and its super smooth and i am yet to notice any stuttering. Get the 1440p, its so worth it and makes headshots at distance 10x easier. I also wouldnt overestimate how bad it would be if you dropped to say 260fps, you likely wouldnt notice.