OK, you are narrowing it down joconnell but I'm not in agreement wtih the comparison.
It is not a case of a 'standard' backpack designed for wilderness travel, vs. a wheeled bag for urban travel. As I noted in the links I gave you to read, the choice between a backpack and a 'travelpack' is made based on which of the two activities you will do more of. So if you tend to always do a fair bit of hiking when you travel, you may decide to opt for a backpack as I do. But if you tend to spend 80% plus of your time in urban environments then you may decide to opt for a travel pack. A travel pack is designed specfically to deal with the issues being hilighted here in terms of backpack vs. wheeled bag. But without the wheels.
A wheeled suitcase or wheeled backpack simply adds the weight of wheels and frame to the weight of your bag. The whole idea of 'backpacking' is that it leaves your arms free at all times for whatever. A wheeled bag cannot do that. Weight is the number one enemy of a backpacker and anything that adds weight that can be avoided should be avoided.
The one time a wheeled bag makes sense is for someone with back problems that mean they cannot carry a pack on their back. Otherwise, they are redundant. Bearing in mind of course we are not talking about a package tourist here or a business traveller. We are talking about what is best for a traveller hopping on buses and trains, walking around in a city with their bag for several hours etc. Imagine running to jump on a local tram in Calcutta while dragging a wheeled bag behind you vs. running with a travel pack on your back. Scroll down a bit on this page (ignore video at top) to see the scene: http://ca.phaidon.com/agenda/photography/video/2011/october/27/steve-mccurrys-one-minute-masterclass-2/
So instead of comparing an 'expedition pack' (which no one is suggesting) to a wheeled bag, compare a normal backpack in the 30 - 50L range to a travel pack in the same range. A good example of a quality travel pack is the Osprey Farpoint 40. http://www.rei.com/product/837010/osprey-farpoint-40-travel-pack
Pictures:
http://www.google.ca/search?q=osprey<i>farpoint</i>40&hl=en&tbm=isch&tbo=u&source=univ&sa=X&ei=7NkwUeyxFIaVyAH7yIG4Dg&ved=0CEkQsAQ&biw=1280&bih=687
No hotel will turn you away if you walk in with the harness zipped away and holding it by the side handle. It is fron't loading (your preference). It is less awkward on a crowded train/bus than a wheeled bag. No check-in issues. Features like pockets for tablets and laptops more suited to an urban traveller than a wilderness traveller.
I'm not suggesting this particular pack for you, it's simply an example of a well designed travel pack.
