I followed your guys' lead and got your Deuter backpack as well for my world travels (currently on the itinerary: Philippines, Maui, California, Germany, the rest of europe).
You can see some photos of me with it on my site http://www.thedigitalbackpacker.com
I am 6 feet tall, so you can see how small the backpack is on me. It is VERY doable though, even in cold-weather climates. Just get ONE jacket when you get there, and wear it all the time.