The rain cover has good protection. Whether additional protection is needed is more of a personal preference.
I checked this bag all the way home from Southeast Asia. I wrapped the hip belt around the front of the bag, cinched everything down tight, covered it with the rain fly and added a suitcase compression strap to the outside.It was a tight, slippery bundle without any good place to grab, so I bought a suitcase compression strap and laced it behind the back suspension and around the front. This gave the baggage people a good way to move it around. It worked very well and I could still wear the pack.