Hello, my name is Kamil, know as Lainkml, i test today a Witcher 3 on DX11 and DX12 and i have some suggestions:
Re-implementation of Raytracing and DLSS/FSR for DX11 i think its better option then stay on DX12 (who been young driver and still unstable - look at Borderlands 3/Dying Light 2).
DX12 - Its new driver technology but still young and unstable then DX11 who been updated for 10 years (idk about that, sorry for mistake). With every technology used on DX12 - i mean FSR2, DLSS3 and other types i have only stable 30 fps on the same settings like in DX11
DX11 - its better and stil good perfomance driver, when im play WItcher 3 Next-Gen in cutscenes i have 110-120 FPS, on gameplay with huge amount of NPC/less amount of npc (cities/villages) i have stable 55-80 fps)

Question for CD Project Red:
If its possible to implementation of Ray-tracing technology/DLSS/FSR2 on Directx 11 too? with Nvidia Reflex (anti-lag technology) of course. For the DX11 is more stable and getting more perfomance boost then unstable DX12.

Best regards from Poland, have a nice day,
Kamil aka Lainkml

P.S - My PC Spec is used for Witcher 3 Next-Gen Update:

Asus GTX 1660 Super 6gb
Intel Core i7 6700 4x3.4Ghz
16GB Ram HyperX DDR4 3200 Mhz
SSD Drive Goodram 1TB
144 hz monitor LG with free-sync/g-sync technology

Dx11 stutters, dx12 stutters, dx12 with nvidia reflex reduces the stutter a alot, preffer low fps and less stutters than high fps and stutter every second.