Originally Posted by Batmanuel

Hundreds of coin dealers fly every few months to attend coin shows with millions of dollars in hand-carried coins/currency/bullion. (I'm a currency buff myself)

Coin forum threads about first-hand dealer experiences differ greatly from the "doom & gloom" guessing in this one. I'm sure there are many stories of Ma & Pa losing their rare coins and such during bag checks to opportunistic thugs. However, I don't recall any stories about coin dealers having the same theft issues with TSA. I'm sure that going in with a large "inventory", knowing what to expect, and requesting a controlled search environment differentiates you. As long as you hand-carry, and nothing of value is checked in, you should be fine.

Travel with a friend, if you can, and bring all of your valuables as carry-on. Its usually possible to get the X-Ray operator's attention, and then to let him know the bag you're about to send through will need a private screening. If you're pretty paranoid, ask that at least one of the screeners checking your bag to be a lead. Two screeners will be in the room with you, and you and your travel companion should have a clear line of sight on both of them as they go through your things. When they're finished, let them know you'd like to repack yourself, and do a mini-inventory of all your belongings before you leave.

Here's a good read on the subject, if you have the time. It's a little dated, (FAA regulation number #108.9???), but the general information is still relevant. Flying Wise: Security in the Skies.