Just a datapoint to those who have been subjected to questioning while using GE. I went through SFO yesterday. I printed out my receipt and as I was walking pass the nearest kiosk, the CBP agent, who was processing a passenger, asked me to show my receipt. I waved it to him, standing about 10 feet away, and he said thank you and told me to go ahead. He didn't examine my passport or receipt. I showed my receipt at the exit of the Immigration hall and proceeded to wait for my luggage. When I exited the Customs hall, the agent just took my receipt and said welcome back and that was it. So if there was a "trend" towards asking questions and examining passports, it's not evident at SFO which has not changed from when the machines were installed there.