#9, this is generally true, but I went and bought an Eagle Creek 3 years ago, anyway, at a Very High Price. I'm a budget traveller by principle, do not splurge on things, but I saw whatever I bought as an important tool for my travelling lifestyle (2-3 month trips to Asia and Africa). I should mention that I love it to bits :-)

What kind of work will you be doing in those countries? Will you need work-office clothes and meet people work wise or is your work independent and only by yourself?
Makes a huge difference if you need office clothing or not.
I wouldn't recommend a duffle with wheels as the frame sticks uncomfortably in your back and 100l will be very heavy but as it's what you ask for look at High Sierra luggage. This one is just over 100l.
http://www.amazon.com/High-Sierra-Bottom-Wheeled-Duffel/dp/B004XYL1MK