So I got the two new characters and, as expected, I;m not using them at all. I find that the team you get throughout the game works really well together and the two new additions come very late, but at the same time, the way experience works - in that anyone benched gets all the experience anyway, whether you can swap them in at a given point or not - still makes it flexible enough for me not to suffer any consequences if I ever DO decide to swap them in.

The original four work so well, though!