My experience with DX11 so far has been great with a few minor issues I'll list here.
While I was riding my roller beetle through Jahai Bluffs, terrain and UI elements/text randomly started disappearing/reappearing at random. This has only happened once and was fixed with a game restart.
There were significant stutters that my whole fractal group experienced only during the ghost labyrinth section of the Siren's Reef fractal.
The colored tiles in the dwarven treasure room in Thunderhead Peaks all appeared green and a restart fixed them.
https://i.imgur.com/isPWdjR.jpg
Outside of these small quirks I've seen significant improvement to frame pacing and higher frame rates in previously very taxing areas such as the middle of Lion's Arch. The dreaded stutter on camera movement is also completely gone.
My hardware specs:
Ryzen 5 3600
16GB DDR4 RAM @ 3200MHz
RTX 3060 Ti
Kingston A2000 1TB NVMe SSD