I've only used a trailer when touring with my Bike Friday. When doing a one-way tour and flying back the trailer box is also the suitcase that will hold the bike and trailer parts on the flight. Works fine and connects/disconnects easily in a couple seconds when wanting to leave the luggage somewhere and ride an unloaded bike.
But generally I still prefer to use panniers to minimize the overall weight. I try to keep my touring load down to about 20 lbs. and adding a trailer adds a substantial amount to that. If I were touring with a load of 40 lbs. or more then I would reconsider use of a trailer.