I agree that the biometrics don't really speed up anything. And I'm not sure what it is like for a I-D connection at SLC.
But as a data point, here's what happened last time I departed from ATL on an Intl flight:
- OLCI night before
- Dropped curbside
- At TSA, looked at a camera; ID and flight info confirmed, passport and BP stayed in my pocket
- SkyClub - checked in with eBP, but I had to do a doc check so SC agent scanned my passport. Also got a paper BP on request because I just like paper for intl flights
- At gate, looked at camera similar to TSA. Slip printed with same seat assignment as I'd had all along. No addl doc check.
Seems like a lot of technology for no real purpose or benefit (to the passenger) other than looking cool.
At the end of the day I still need my actual passport to travel, and I still end up with a piece of paper (or two) with my flight info and seat assignment.