Yeah, last year was a nightmare travelling, they wouldn't let me bring my LiPos outbound. So I was screwed. Then I just about got two US Customs officers acting like jerks. I was told they're trying to shake you up, see if you're legit or not. I dunno. Then CATSA Xrayed my stuff while I was there, no search. On the way back TSA searched my crate while I wasn't there, and messed up my packing, luckily didn't damage the heli.
This year, I got the batteries on the plane with little problem. They swabbed them, all good. But then US Customs took me over for their own Xray of my equipment. Then they asked a bunch of dumb questions. When I told them I was going for an RC Heli competition, yeah, same deal I got the "Whachu talkin bout Willis" looks, but eventually they let me go. Then again CATSA Xrayed my equipment right in front of me, which was good, they didn't bother opening it.
On the way back from Denver, TSA let me board with a ton of LiPos, they barely looked at them, didn't swab them, nothing. I actually didn't like that. They should at least be swabbing these things.
I learned a few things:
You really need a proper case, like a Pelican, with cutout foam. You can't rely on somebody careful packing the equipment. TSA needs to be able to open it, look, and close it. They won't take care to replace all your packing material properly.
But also don't be too conspicuous. Last year, my Lipos were taped up, put in fire-proof bags, then in a Pelican. They took them. This year, my lipos were loose, and I just stuck them in a lunch box cooler bag. Nobody looked at them twice.