After LOTS of research, this carryon is the one I chose.  Research was worth it - I love this bag.  It is well-made, sturdy, rolls straight, my laptop was safe from Michigan to Sydney, NSW, Australia and back, and easy to lift (extra hand-hold on the bottom helps).  Only slight misgiving is that when I loaded my smaller bag on top and looped the smaller one around the Travelpro handle, the whole configuration was unsteady and actually fell over once when I was not careful.  Once I anticipated the need for extra caution, the system worked fine.