Originally Posted by drewguy

A more helpful way to look at it would be this:

What is your average time waiting to clear immigration at Dulles? Subtract 1 minute from that. The remainder is the average time saved.

The hang-up at IAD is baggage claim. If you get through immigration in 1 minute, you still have to wait for your bags to appear. If, however, you carry-on then I have taken less than 5 minutes from hitting the arrival hall to sitting in a taxi. On one trip I avoided the immigration lines only to watch passengers from my flight pass me into customs when I had to wait until my bags hit the carousel, just about last.