On my most recent trip, I was concentrating on whether or not my Soft Cell would be checkpoint friendly, but I also achieved another milestone: a longer-than-overnight trip with just my "laptop bag".
I'm really pleased with the second slot of my Brain Bag, and how much roomier it is than the "daypack" of my Eagle Creek rollaboard (the bags that are now relegated to permanent dust-collecting in the corner of my room).
As an experiment, I decided to forgo the usual "laptop bag plus clothes bag" routine for this recent 5-day trip. Keep in mind that as a guy in relatively warm weather, I can get away with a single pair of pants and a few short-sleeve shirts for a 5-day trip, counting my "all black day-of-travel spill hiders" as one of the sets.
I recently purchased the Convertible Packing Cube to replace my Eagle Creek-equivalent for holding my toiletries, and double as a fanny pack for the light day trips at my destinations. I normally stick this in one of the end slots of my Aeronaut.
I also purchased the Convertible Packing Cube/Backpack to replace the "main" cube inside my Aeronaut. I'm intrigued by this unit again for its dual-nature... it would seem to be not much more bulk than the large packing cube (in which I'd held my shirts and pants), but double as a light day pack on the road, for those days where carrying the entire Brain Bag would seem like overkill. (I often find myself carrying just my laptop and partial loadout of camera gear onto a cruise shore-excursion for picture taking and cheap internetting.)
So for this 5-day trip, I loaded up the Convertible Packing Cube with my toiletries (no liquids!), and my CPC/B (Tom Bihn needs a better name for this) with 3 t-shirts (from http://scottevest.com) and undergarments. Those two cubes fit comfortably in the second slot of my Brain Bag (sitting below my Snake Charmer for the electronics cables), and my laptop and Soft Cell were happily in the first slot already. I was concerned that this would make the laptop unwieldly large or overly heavy, but neither turned out to be true.
I happily made my journey from PDX to ATL and back for a 5-day trip, using just my Brain Bag to hold all of my laptop gear and clothes. Yeah! Thanks to Tom Bihn for making the most out of a little space!