On December 28th White Lands MetalRT GPU 2:50:38 / Metal GPU 2:34:50I will give a try, I have my render times for previous versions and could figured out improvment.
Now White Lands MetalRT GPU 2:40:63 / Metal GPU 2:26:06, there is a slightly Cycles improvement but as developers says this update has effects mainly Evee and UI.
There is a quite big improvement about UI overall, everything works better and updates faster.
That's all I can observe.