There is a short line in SFO Terminal A about 50% of the time (I seldom arrived in Terminal G). When I joined GE, there were two machines and they were usually idling. These machines had difficulty reading my fingerprint. Now they can ready my fingerprint without problem, there is sometimes a line even with four machines.

It is difficult to say how much time I can save with GE as there are usually few passengers in the US Citizens lines when I arrive, but I have never had my luggage checked since I joined GE (perhaps just my luck).