Having a military ID, I've never had any problems with TSA, Boarder Patrol, or Homeland Security.
Northern Utah: I was taking pictures outside of a missile construction facility, Homeland Security asked to see ID, then said to have a nice day.
Later that same day in central Idaho: taking pictures outside a nuclear research facility. Same thing: asked to see ID, bid me a good day.
Travel for Thanksgiving and Christmas at several airports: 2 GPS devices, using them before and after security. Not even a blink.
Boarder btwn Seattle and Vancouver: never been searched, just asked where I'm going and where I'm from. Not even what I'm doing!
Now that I'm getting started on Geocaching, I think I'll try to stay paperless as much as possible.
Stealth Ninja Geocaching.