I just took 11 flights through Australia, Asia, Middle-East, Russia and Europe and had no problems with my 10kg camera bag. The trick is that it looks pretty small (Kata 3N1-30, fits well within the carryon size limit) and I'm pretty big/strong, so it looks light when I carry it and no one picks on me. Nowhere did I see airlines weighing all carryon as a matter of course, but I wasn't in the USA where I think that might be more common. I had a couple of security-check people go "oof" at the weight and a couple of very detailed inspections in Russia (120 rolls look like 12-gauge blank shells, sort-of), but security are only responsible for things that go bang, not charging you for overweight luggage.