How replayable-4xish is this game?

[Poopsi]

To fill you in, I might just buy myself something to congratulate me on the exam which I think I just passed, and I am considering some of the Sharpnel games. This one in particular drags my eyes because I find the concept of sailship combat highly desirable. I am concerned on how lineal (or not) the game is, however. Personally, I´m addicted to 4x games. I know this is not a 4x per se, but I´m wondering to what extent it can generate random campaigns/scenarios/whatever, and hopefully have those be somewhat lasting.

For the record, I´m also looking at BCT commander, and Weird Worlds...