I haven't traveled with this backpack yet, but plan to in 5 months.  As soon as I purchased it I packed it with everything I would take on the plane, and this bag is going to work wonders!  Lots of room, lots of pockets and high quality.  I love the zippers, as they smoothly zip and unzip without any snagging.  I've tried it with the back pack straps, shoulder strap, and carrying it as a traditional bag, and actually for temporary use, I like using the shoulder strap.  I think the shoulder strap works fine if your bag isn't too heavy.  I'm packing the least amount of items possible and my bag will be very lightweight, and the regular shoulder strap works just fine for short distances or while standing in line etc.  I purchased a Rick Steves Toiletry bag (small) and it fits perfect in that top zipper compartment where you can also put TSA liquids.  I like to have immediate access to my toiletry bag while traveling, and this fits the bill.  I also love how the bag cinches down really well with the 4 straps/buckles.  I was initially going to purchase the Rick Steves convertible, and after looking at the videos of both products, it didn't take long at all to figure out which one was more superior.  I also looked at the Osprey Meridan and the Eagle Creek Switchback, and I ruled them all out, and chose the Mother Lode.  The thing with the Osprey and Eagle Creek models, is the fact you have to take the day packs off to make them "carry-on" legal, and I'm not so sure I want to keep removing and reattaching the day pack when I get on and off the plane, as you can't carry both on your back at the same time.  Going through all the scenarios in my head, I decided against those types of packs and providing myself with a frustration free airline trip by using the mother lode.  I love this backpack!

July 26, 2012 (UPDATE):  So far, I've taken this backpack on a greyhound bus across the country, and on several airlines.  It still looks new, and nothing has frayed or broke.  I carry everything I need in this backpack.  I carry 4 pairs of pants, 3 shirts, a variety of socks/undies, all my toiletries and first-aid kit, a universal backpack stove, MSR mini-works water filter, and purification tablets, dehydrated food, sea to summit towels, inflatable pillow, sea to summit collapsible bowls/cups, rick Steve's micro-fabric daypack, kelty rain jacket, 2 nalgene collapsible water containers, light sleeping blanket, in-flight inflatable neck pillow, money belt, RFID neck passport holder, joos orange portable solar charger(stored in the rear laptop sleeve), and a few other miscellaneous item.  I pack these items in the event I get stuck somewhere, I'll be able to filter and sanitize any source of water, and eat.  I also purchased two (2) handle cushions that really make the handles very soft and cushions where you can carry the bag for an extended period of time and it will not hurt your hand.

I also purchased 2 clinching straps that I wrap around the entire backpack for bus travel, as this bag is too large to fit inside of a greyhound bus overhead. The straps keep everything secured while being shifted around or thrown around by baggage personnel.

Next year, I will be traveling to Europe and this bag will be getting a work out.  I wouldn't trade this bag for any other on the market.  When I return from my Europe trip, I will leave another update.  Oh, and this bag felt just fine using the sternum strap walking for distances.  I actually didn't use the hip belt yet. But, I also like the shoulder strap a lot too for short walks in the airport or bus terminal.

UPDATE 12/5/2013

I arrived back from my Europe trip a little over a month ago, and this backpack held up the entire trip. What amazed me is the fact the zippers on this backpack are extra heavy duty, because there were times I had this thing stuff to high heaven and none of the zippers busted. I was on trains, buses, trams, ferries and airplanes for almost 6 months from as far north as London to the south in Croatia. I packed mainly summer dresses and had all my emergency supplies (bug out bag contents) with me too, including some food and cooking supplies just in case I got stranded or something. I had everything I needed and believe it or not, I used everything I brought along. And it was a lot believe me. But, I had no issues carrying this on my back as long as I packed it correctly. Just make sure the area touching your back doesn't have anything protruding out that will put pressure on your back or lower back. Once that's taken care of you're good to go.

This backpack really shines when you need to maneuver up and down stairs and in small passage ways. Above all, being able to carry this bag on the plane is the upmost important attribute this backpack has and I wouldn't trade this in for anything.

*there were some regional planes where this bag was too large to carry-on, but I just checked it in the holding cabin as I walked on to the plane, and claimed it as I walked off. So, no baggage claim at the carousel was necessary at the airport.

If you're on the fence, buy it, its well worth it!