I bough this Duffel Bag to complete my WT4.0 luggage set.
It is an excellent carry-on, with enough space for all travel gadgets (travel neck pillow, headsets, cameras, etc.) and one day worth of clothing (in case your luggage arrives late).
I had to decide between this bag and its baby siebling.  I'm happy I picked this!  It turned out to be extremely practical!