I have a no-name rollerbag whose dimensions fit the *new* United carryon sizer. But I am always cramming it to the hilt to make everything fit for 3-day business trips (including workout clothes and room for shopping finds!) so that 9" may be a game-changer for me to comply.

Do packing cubes really help to flatten clothes? If I make the investment, is there a brand out there that's better than others?