The 787 will be more comfortable than previous aircraft, but its performance is not solely the result of a composites fuselage [unless you count GLARE as composites as well…].

GLARE is certainly a composite material. It is very different from CFRP, though.

GRP & plywood are other composite materials used in aircraft construction. I wouldn’t want to say that any particular characteristic of cabin atmospheres was common to aircraft using those materials, or due to their use.

“Composites” is an over-used word in this context. It is insufficiently precise, & is often misused to mean CFRP, ignoring other composite materials.