I recently updated to patch 1.61, though in-game it reads 1.60 and I'm playing on a 1080p tv with super sampling enabled. The differences are very obvious switching between 1080p and 4k. Firstly, 1080p super sampling has disappeared entirely and must be enabled in system settings. Second, the pop-in (trees in the distance mostly) is horrendously bad while in 4k mode. Also, while in 4k on a 1080p screen I've experienced an occasional stutter, once while mounting my horse and again as I jumped into the water to retrieve an item for Triss during the mission in which the player must aid her in getting rid of a rat infestation in Novigrad. During the same mission's ending cut scene Triss still had a fire ball in her hand while speaking with Geralt. I also recall a random guard moving about like a ragdoll during another cutscene earlier in the game when reaching Triss's house, where the player comes across the two looters (also noticed a texture disappear on a wall of her house during the same scene) . It is apparent that all these months of waiting for the CDPR team to fix the framerate drops and implement HDR have resulted in an unacceptable and entirely unplayable experience, and what a shame it is that you guys waste time on cheap gimmicks like hdr and whatever so-called improvements made to the 4k checkerboarding that only create more bugs. The best experience was patch 1.31 with boost mode on ps4 pro and I wish the 4k mode acted the same as it is very nice to look at indeed.
For all 1080p users, I can confirm that the popin is greatly reduced and the framerate is solid so far when in this mode. I've yet to see any cutscene related problems...yet. So 1080p with supersampling disabled is the way to go for now.
FIX THE 4K MODE, the world is still playing catch-up with HDR and is heavily dependent on the tv screen capabilities anyway.