This 600 PF is a very exciting lens! It starts with the lack of weight.
I've come to value a very light supertele more than I do the versatility of a zoom.
These PF's are in a class by themselves. Still do not understand why other manufacturers have not started developing/offering them.
This lens checks ALL the boxes for professional grade.
Regarding the 6.3, who cares? If it was 5.6 it would be too heavy. And with these mirrorless bodies I'll bet that even with a 1.4 it will be tack sharp.
