I have in my hands some 4x5 HIE, which has been refrigerated since purchase in 2001. Plane travel between me and my 4x5. Should I get it shipped home? (But what if they loose it?) Take in my carry-on? Ask for it to be hand examined? (What if they insist on scanning it?)
Personally, I would ship it home. Send it overnight or second day service, insured and with a tracking number; you should be okay. I have done this when traveling "with" infrared film, and haven't had a problem.
I recently had a whole bunch of very old HIE shipped to me via the USPS with no special precautions taken. It was fine. I just popped it back in the freezer when it arrived. That which I have shot was no worse for wear.
I would just take it with me. I travelled from Japan to Australia, with 4x5 HIE. X-rayed several times with my carry on and no problems. I would not feel safe mailing it. It could be opened.
And hand examine today means, "can I open it?" That's what happened last year when I was leaving Japan with a stack of 4x5 Acros. They wanted to open it. It ended up going through the scanner with my carry on. No ill effects whatsoever.