Two are better than one. I'd say two are better in terms of organization, flexibility, safety and weight distribution. Ideally the two bags are such that they can be combined if there is a strict one bag rule.

I think it makes perfect sense to have one bag that contains the most valuable and important items that can go under the seat in front of you. That means it will never be separated from you thus safe and easy to reach making your trip more efficient and comfortable. Even safer, because if you don't have to get up to get something out of the overhead bin there is less risk of tripping or of stuff falling out of the bin onto you or other people.

Since the personal item usually contains the tech equipment it will probably be almost as heavy as the luggage item even if the luggage item is bigger in size. So weight distribution can be handled to better suit you than it could be with one bag being carried on one side only thus throwing you and your back off balance.

Obviously, the overall weight should still be as low as possible so that wheels can be avoided altogether. But if that's not possible I guess it's better to have wheels (for ordinary business travel in urban situations) than to risk spinal health, so to speak.

Here is a post that I wrote on 1bag1world that actually resulted from a similar discussion we had here on FT:
http://www.1bag1world.com/obow-light...um/post/894037

My views on the matter are unchanged. I'd even go as far as saying that it is wonderfully "sans soucis" if you can actually check one bag and only have to carry a personal item which has all the required stuff even in case the checked bag should be late or lost. Sure you still have the trouble but you won't be SOL.

Till