Now that I've been thru it, I'll add my experience...

Due to traffic concerns, I did wind up taking Metro. However, there was little traffic on the Parkway or airport roads and I could/should have stuck with my usual Uber. With no checked bags and mobile boarding pass, getting to security from Metro was a breeze - probably a 30 second walk from the Metro exit. In the future I will definitely use the "Express Passenger Drop Off" mentioned above by DCA writer. That is a quick walk to the same point where the Metro station exits into the terminal.

Arriving about 7:45am last Thursday, I made it from the Metro exit to my gate in about 15 minutes. Very easy - why I LOVE DCA!!! There were probably 30 people in the PreCheck line and (as also pointed out by DCA writer) many were redirected to regular security since PreCheck is first (a nice feature!) and people just blindly went into that line. [Whatever happened to the airport agents checking boarding passes at the PreCheck entry???]

Overall, I'm very impressed with the new layout. MWAA did a nice job with this, and there is a lot of helpful info (including videos of the new process) posted on their web site.

Only remaining question is which checkpoint to use. MWAA directs all AA to north and everyone else to south. In theory that means south should be less utilized (all commuter terminal, all north pier, and most of middle pier (AA) to north and only B6 in middle and south pier airlines in south). Next time, I'll try the south checkpoint.