When I travel, I carry on my regs, computers and camera equipment. It all fits nicely into my Pelican 1520 with my laptop and external hard drives and meets the requirements for carry ons. I pack in a backpack to go under the seat my mask, swimsuits, a couple of changes of clothes (in compression bags), my glasses/contacts and my Kindle and travel documents and other valuables. I wear the Tevas. Everything else gets checked. I pack batteries (I use rechargables) in the dive lights and strobes upside down so nothing gets turned on by accident. The one issue I run into depends on the water temps where I'm diving. In Bonaire, I need only a 3mm. But in the Pacific Northwest (and here at home in NY), I need my 7mm, 3mm core warmer, hood gloves, etc. I am still working on streamlining the packing for travel and love my Mares dive bag. However, my BC is the biggest space pig and I am thinking about investing in a travel BC which weighs less and takes up less room. Compression bags are your friends. You pack better and can possibly fit more in your carry on.
I haven't had bags lost (yet), but do tend to fly in reputable airlines and look for direct flights. Less chance of something getting lost if it doesn't have to get off the plane until I get to my destination. Also, flying out the day before is awesome. I arrive refreshed and I might have even gotten a morning shore dive in if I'm meeting a live aboard later in the day.