I spent the first six months of this year on a trip that took me from Beijing, to Canada, to Poland, Czech Republic, Germany, Thailand, Cambodia, Laos, Vietnam and back to China.
I took a Leica M2, a 35mm, a 50mm, and a 90mm. I only took one camera. Never had any issues with it. In hindsight I would have left the 90mm at home. It was used too little and I could have gotten most of those shots with the 50.
I also took 120 rolls of film. 100 rolls of Arista 400 premium and 20 rolls of color. The key thing for me was a ND filter. The sun in S.E.Asia is BRIGHT!
I would guess that I went through 20 x-ray machines (could be more) and there were no issues. I never bothered to try getting a hand inspection.
The key to the film is to take it out of the boxes, alternate the canisters right side up and upside down. I taped 5 rolls in a row and then stacked them like honeycombs. actually was quite manageable for space. Weight was a bit heavy, but not THAT bad.
I never had problems in any city, including Saigon at night. Just keep aware of your surroundings and keep the strap wrapped around your wrist.
Most important, enjoy the trip.