Normally I commute from Philly to Paoli with my folder but today I had a mtg in New York so I was on Amtrak headed for Penn Station (sans bike).
I was surprised, but on both the morning and afternoon train I saw a folder!
In the AM (7am out of Philly to NYC) a guy w/ his Brompton, helmet-mounted lighting and all. at NYC he said he goes to Grand Central then takes Metro-North into Westchester.
In the PM (5:10pm out of NYC) a saw a guy get off at North Philadelphia with a Dahon.
Don't know if either of you are on the forum, but it makes me happy to see others with folders on Amtrak.