Fire Ingress
When comparing alluminium fuselage structure to composite, I would have thought one of the most important measures is how long it takes an external fire to breach an undamaged fuselage. I appreciate the fuselage of the A350 at Haneda may have been anything but undamaged, however, it seemed to stand up reasonably well to the extenal blaze. I am not in any particular composits vs alluminium camp here, although, to make a comparison with the Manchester 737 disaster in the 80's, it according to wiki, it would seem that fire burned through the fuselage in less than a minute, and last survivor was removed by fire crew after 5.5 minutes. However, this was a big fuel fed fire with the hot side into wind, so admittedly, a different scenario.
Disclaimer: lurking SLF here, no aircraft industry knowledge apart from a knowledge of what burning composite smells like having done ultrasonic bonding trial for the industry.