Hi Andreas, thank you for using FFAStrans and welcome to the forum!
First, FFAStrans is hardware independant and will stay that way for a while.
Second, there are several issues when it comes to using NVIDIA GPU for professional formats. And that is; you simply cannot do it. Most professional formats is in 4:2:2, the NVENC only supports 4:2:0 and 4:4:4. So you cannot create f.ex. "standard" 264 flavours like AVC-Intra and XAVC. You cannot create any MPEG2, DNxHD, ProRes, Cineform or anything like that. Sure, you can allways create high bitrate 264 in 4:4:4 files but they will not be withing the realm of any "Professional" formats. Add to that the limited number of simulatneous encodings on consumer cards like the 1070/1080, you might be able to create maximum two files at the same time. So you see, there are several "professional problems" with the NVENC approach.
BUT, because FFAStans lets you create your own custom ffmpeg encoding profiles you can always experiment with the NVENC encoder yourself
-steinar