One problem with Gmail is that it doesn't appear to be possible to download all your email as a text file, as used to be possible when using Eudora long ago.

Having once lost all my mail when the merry pranksters at Eircom deleted my account and all the mail on it after I didn't use it for some time, I'd be eager to do this and then clear my mail from Gmail, in case of horrid accidents. Years and years of research there, and I'm not always that efficient about saving essential mails and addresses.