I think that the intuitive advantages of an S&S touring bike are much less in practice.
Fitting a 700c bike with racks and fenders into a standard airline sized case is nigh on impossible. You're going to need a seperate bag for panniers, water bottles etc, and the rest of your gear apart from hand-baggage.
With airlines going more and more to a single piece policy, but also having sporting equipment policies, the cardboard box maxed out to 23kg and a pannier as hand-baggage means you're within the allowed free baggage limit.
With the S&S bike you'd be paying a surcharge for the second bag.
This is the case for BA, (Quantas and Air France as well?)
Qantas regulations for destinations not including North America ...
http://www.qantas.com.au/travel/airl...r-destinations
And this is a perfect example of why a person needs to check, and check, and check again when it comes to flight regulations.
If you were flying from Australia to Canada, you'd be allowed 2 pieces (maximum 23kg (50lb) per piece)
http://www.qantas.com.au/travel/airl...l-the-americas
But all these rules and regs, and the fact that they change with the wind, is one of the reasons why we'd go with folding bikes next time we take off for a tour.