Most of the time, when traveling on the smaller "toy" airplanes that fly in and out of smaller airports, I am forced to "gate-check" bags that would otherwise fit into the overhead bins on larger planes.  I was able to unzip and carry-on the top portion, which contained my laptop and travel documents, and let the airline gorillas and sneak-thieves handle only the bottom portion, into which I packed only clothing.

My only complaint is that the lid to the bottom portion of the bag will not stand upright or fold back, making it necessary to hold it with one hand while packing it with the other.