I got to experience the SeaTac mess this morning. I always feel like SeaTac security is slower than most airports, and today was one of the worst security waits I've ever had. 45 minutes in the MVP Gold line.
I was told by one of the checkpoint officers that they were installing the scanners to "speed up" the security process by the N gates. Right. I'm sure that will "speed" things up.
Earlier this year I was flying United to Chicago where they had installed the body scanners, but after about a week or 2 they stopped using them for everyone and just used them randomly.