Originally Posted by
bseller
Remember that this program is only open (primarily) to US Citizens and Permanent residents. IIRC, the percentage of US citizens who even HOLD passports is silly low.
Quite possibly true, but I suspect fairly strongly that all the people ahead of you in that long slow "US Citizens & Permanent Residents" line at passport control are among that percentage that do have passports, and they're the ones we're worried about.
Having said that, I do believe it won't be too much of a problem. The program isn't likely to attract your once-every-couple-years travelers since it involves the $100 and visiting the airport outside of a normal trip. I suspect you might end up with a short line for the machines, but still significantly better than the standard line.