I have been overthinking this same situation. My plan is to go ahead and get the suitcase trailer combo. Then travel with my panniers and personal gear in a large duffel bag. I have used trailers in the past as well as the panniers and both situations worked for me. I love the idea of being able to pack the bike in a solid case for protection and then not worry about what to do with the case when I get where I am going.
If I were doing an out and back tour the panniers would get the nod, if I were doing a destination to a different destination tour I would go with the trailer and possibly a small set of panniers on the front rack. FWIW I typically run Ortlieb Classic Rollers, on all my tour bikes (I currently have 2 full sized and will be getting a NWT soon)
Aaron
