The repetitive "Finding messages outside of Mail Pilot" sections make me think that it's not going to play well with other clients -- unless it means that it's storing some sort of metadata/copies in those other places, which is not the impression I get (it seems to be saying it will actually make a bunch of folders and move your mail into them, which is Not OK).
Personally I do not want my mail client to be my task manager. I use a Todo list app (Things by Cultured Code) that does a smooth job of linking a todo to an email. I simply create a task linked to an email set for 3 days from now, I delete the email from my inbox and have 1 'inbox' for my actions. I believe the various other todo apps on the mac handle this just as easily.
Seeing workflow wrapped into an email client strikes me as wrong—I want my mail client to be for communication, not for managing my next actions.
http://www.mailpilot.co/bestuseguide.html
The repetitive "Finding messages outside of Mail Pilot" sections make me think that it's not going to play well with other clients -- unless it means that it's storing some sort of metadata/copies in those other places, which is not the impression I get (it seems to be saying it will actually make a bunch of folders and move your mail into them, which is Not OK).