On this trip (and many trips) my backpack is stuffed to the brim and about 2/3 the size of a roller bag. My personal item is my small purse. The backpack can mostly fit under the seat in front of me (as long as I'm in the window seat, not aisle where the space is smaller), but if I put it there, my purse most definitely cannot fit also. There is no logic that can convince me that a person who chooses to use a roller bag deserves the overhead bin space more than I do with my backpack. It is a huge sacrifice for me to have to spend a 5+ hr flight with no leg room because others have chosen not to check their roller bags, as the flight attendant on my flight was expecting me to do. I don't feel that I should have to sacrifice my comfort (and potentially health as less leg room means I won't be able to move my legs as much and will be more likely to get another DVT) for your bag. I board early so that I will have space for my carry on in the overhead bin, regardless of the type of bag I choose to use.