Alternative to the alternative: They're long, so more people can find space and you don't have to end up squeezed in the vestibule like the Piccadilly line. They have the same kind of seats used by million of bums on TfL services as the Overground and, while not exactly an S-class level of comfort, they're better than standing up on the Piccadilly Line. They do serve T5, although at present on weekends only. And they deposit you in Paddington, which is in Zone 1, and (inshallah) will also deposit you in Bond street, Tottenham court road, Farringdon and so on which are all "downtown".