I usually use a PIV-II card and it confuses them about 10% of the time, even though it's the same badge they have, just a different agency. I use it because a) it makes a noise when it falls on the floor, so I'm more likely to notice it, and b) I often need to have it to work at my destination, so I know that I have it. I've dropped my DL and nearly lost it enough times because it's thin and lightweight that I try to avoid using it at the checkpoints.