IME there's been a huge improvement in the last 6-12 months. I've gone from believing the priority tag to be a waste of time, to finding that it works an absolute treat, on both international and domestic arrivals in the US. I've experienced baggage claim at SFO (many times, both domestic and international), JFK (a few times) and IAD (a couple of times) in this period, and I tihnk in every single instance my (our) bags have come out right at the head of the queue.

I'm developing faith.