Instapak is nice but it does not conform to the new 20 x 14 x 9 in regulations that most US airlines enforce / will enforce.
See post at http://forum.dji.com/thread-49353-1-1.html for more information about flying with an Inspire
Another reason I like the c11. I recently traveled with a DJI F550... Folded the arms down and slid it into a backpack. Didn't even have to lace it in the overhead bin. With the c11 you should be be able to do the same