Without 10 seats abreast in economy 777-9 has nearly identical pax configurations as in a350-1000.
Nobody in his right mind would operate a 779 at 9 abreast - that made sense with previous 777 versions up to the 77W. With its resculpted interior, the 779/778 is designed to be operated at 10-abreast.
The A35K is the same size as the 77W. The 779 is larger, which can be an advantage (better CASK/CASM when the seats are occupied), or a disadvantage (fewer airlines need a larger and heavier aircraft).