Just a little first hand experience traveling light and some of this may be a little off topic but maybe some will learn from me. I started out 8.5 months ago with a 37 liter pack with a 13 litre daypack(it was the discontinued North face backtrack 50, it was bomber as rock climbers say). I have now crossed the entire south american continent, and must say having that size of pack paid off. I was able to carry it with me and put it on my lap on trains, crammed full taxis ect. Even on the overhead bins of some buses. This came in handy in Bolivia, where I have heard many packs walking away from under the bus. But I have learned the hard way, and my lovely small pack that was right behind, walked off the bus in Columbia. I half blame me for it, and it was at night and unfortunetly can never leave your gaurd down( I was about 15 minutes from the bus terminal and my pack fell on the ground, but left it there seeing as the woman beside me knew it was mine. Fortunetly for me, I always keep all my important stuff, be it credit cards, passport, camera with me at all times on any transport. They managed to get all my clothes and my chargers, with the chargers being worst of it. Anyways I learned a couple things. The best way to pack is to pack like your backpack was stolen(Heard this a few months back from a fellow traveler). So start with the essentials, get your toothbrush, toothpaste, deoderant, ect.. If you work at it from that angle, and then add just bare minimum clothes, you will be surprised how little you can get by with. And of coarse, now that you have a smaller pack, its also easier for someone to make-way with your pack.
So when I get back to Canadian soil in less then two weeks, I am planning on trying to go ever lighter. I am looking at trying a pack under 30 liters. I think its manageble. I will let you know when I got a packing list. Happy travels everyone