We NEVER put our pins in our checked baggage because, even though we've never had a lost baggage situation, with our luck that would be the one time something would happen. Of course, everyone feels differently and some would rather check the pins than deal with any potential hassle or delay at security. Still, be prepared to check the pins in case a security agent says they have to be checked or confiscated.
We have always carried our pins in our carry-on baggage and never had a problem. Going to the Epcot Pin Celebration in September, DW Lauri had the pins in her carry-on. We flew from Richmond to Orlando with layovers in Charlotte. The screener in Richmond was
EXTREMELY thorough, going through every pin bag and container with extra traders we had. There were a couple of instances where we were screened again at the gate, but no problems.
Actually, I think the thinking is that if you have something that can be purchased inside airport security, then it's okay. Charlotte has a
Disney Store within their secure area and sell the TDS pins there, and I'm sure other airports have gift shops that sell lapel pins.