I've read it and I can't help but wonder whether on the really busy routes with people standing in the "vestibule", whether it is just too big, even when folded?
If it's that busy in the vestibule area, I would not go with a Joey. You also have to take the front wheel off, which makes it a fussier folding process and a less stable folded package - not good for multi-modal use.
I don't think you would go too far wrong with most 16" or 20" folders for the shortish commute you have planned, however, if space really is tight on the train, a Brompton/Merc, Mezzo, or Birdy would probably be best...If not, a Dahon would be good choice...