You guys must LOVE traveling with lots of carry on luggage 
These days, I carry on only my dSLR camera bodies, lenses, iPod and maybe a few rechargeable batteries for my Canon A640 P&S little camera. But a dSLR housing and strobes? No way......
I plan my trips with lots of time between connections, maybe even a day or more early in case of luggage mishaps. It's all shipped in the padded divider set from a Pelican 1620 size case. Then this drops into a 6lb. Samsonite plastic suitcase (with wheels!) that looks like hell. I even put duct tape on the latches so it looks some some bum is taking a trip 
Always barely weighs 42 lbs.......dSLR housing, ports, strobe(s) arms, cords, spare parts, etc.
Plus my tool kit, shipped thorugh in this case is a Swiss Army knife, two small phillips head srewdrivers, one allen wrench set, o-ring grease, Q-tips (yeah, I know, use the new ladies foam eye makeup sticks instead) plus a couple brightly colored guitar picks for removing o-rings safely.
I have never been on a dive boat or to a dive resort who didn't have crescent wrenches, drills, soldering irons, hacksaws, etc. that I couldn't borrow if need be....
Too each his own, but traveling is a pain in the butt already. Complicating it hauling tons of stuff sure doesn't sound like fun to me 
dhaas
P.S. - James comment is also pretty good. Many times just being nice and making the counter people's job less of a hassle can go a LOOONNNGGGG way.......SMILE A LOT !!!!!!
