You might want to consider how you plan to pack a coupled bike if that is what you end up with. In order to get the bike into a case meeting the airline's criteria for checked baggage, the racks and fenders need to be removed along with other components to allow your bike to fit in the case. Think about how you are going to carry the racks and fenders, plus all you other gear.

My wife has a coupled Co-Motion touring bike, and we have not uncoupled it for any flying trip. It just was not worth the hassle. Her bike has 700c wheels which makes it even more of a challenge. Based on our experience with her bike, I'm not sure that I would get couplers, if I was getting a new bike (I'm not).