Anyone tried this beta version yet? Any idea how stable it is?

Performance parity? Heck no, not until this bug with the GSP firmware is solved: https://github.com/NVIDIA/open-gpu-kernel-modules/issues/538

I been using the open kernel driver with my Debian Workstation, it has worked better then the default driver by far with the Debian backport Kernel, I installed it using the Nvidia Cuda Repo.

Woohoo!