I have to agree with Leadfingers in-that the type of case you transport your guitar in is very important. Unfortunately I did not follow that advise some years ago when an attendent at LAX let my Taylor 510 hit the tarmac. It was in a gig bag instead of a hard-shell case. The result was that the back was separated from the sides at the bottom. I just got it fixed last month.
On the effect of weather on a composite, I had an Ovation where the neck became tweaked because I moved from Ohio to California. Not sure if the tweaking was due to warpage of the wood neck or the fiberglass body. A luthier fixed it for me.