Got a Porsche transfer yesterday in SEA on my first trip as a Diamond! It was perfect because I was texting a friend complaining about arriving at the S gates and leaving from the D gates (not a typo - I learned there are bus gates at ground level there) and didn't even have this service in mind, so I was really surprised and happy when I saw an agent on the jetbridge right outside the plane's door. There wasn't enough time for a lounge visit anyway, I got a scenic tour basically around the entire airport, and the agent was very friendly. Great experience!