What airline actually checks the weight limit on carry-on bags? I've never had mine checked for weight and I carry a backpack that looks like it shouldn't meet the size guidelines, but does.

It depends on the route, but I saw this done on many flights from mainland China to Europe, on several airlines.

(And considering the amount of carry-on luggage that people routinely bring in Chinese domestic flights, this is not surprising; there's a limit to what the overhead lockers can take, not to mention that pathetic slot where your feet should be.)

Not OP, but anecdotally, this happens a lot outside the US. The most recent airline to make me weigh my carry on was Qantas, but I don't think it has ever been required of me within the US.

If it was for work reasons I'd just ship them.

Ironically, for people who travel a lot, the exact opposite happens and we are frequently "encouraged" to use our baggage allotment to reduce courier costs for the company.

The business model is obvious, and has been tried at least once: http://qz.com/309185/this-startup-wants-to-pay-you-to-fly-wi...

Particularly for confidential things, or when in real hurry, I really can't ship it, I have to carry it along.

A typical case is that we have software in development, I'm about to demonstrate it to a customer tomorrow, and before I leave for the trip, I'm making the final build and tweaking of demonstration data set at office and installing in the laptop that I use as a demo server.

By the time I'm ready, the DHL shipments for the day have gone and if I ship it, it would be there one day after my demo. So it has to be in my luggage.

Yes, checked-in luggage may also be lost and delayed, but with direct flights, I'll be fine as long as I'm not going to CDG (Paris).