At first it may be not obvious, but the choice do case in the triangle strategy. It affects three things: the ending you get, people who will fight with you, and the battles that are waiting ahead. But for chapter 17, it affects what end you get. Before you, three complex options whose plan do you have to follow: Roland, Benedict or Fredericks?
In fact, in this chapter not three ways, but four . The fourth is the so-called golden path, and it can be unlocked, only by choosing a specific path (among other requirements). But if you failed it, then you will have only three options: the ways of utility, morality and freedom.
In all three cases Roland, Benedict or Frederick will leave the house of Wolffort. There is no other way.
After this branch no longer. You are waiting for three battles in a row, ending and epilogue. Characters are still possible to gain.
As soon as you go through the game once, you will unlock a new game +! Everything is preserved, including levels, so the battles are actually a bit more difficult. New stages of the Mental Mock Battle will be unlocked, and the store will finally finish the stocks of the items you need to improve.
For more information about the triangle strategy, see some other articles here, in Pro Game Guides.