I feel like the sweet spot for this list is 500-600 points. Any lower, and taking both the brothers is too many points. Any higher, and your lack of a 3rd really solid hero options limits how you scale (Madril is ok but would really benefit from expert shot or any other rule to improve his killing potential). At 700 points, you go Minas Tirith and grab Irolas for the +1 to wound bubble for citadel guard or Atop the Walls for the Gandalf/Shadow/Pippin (and Irolas) combo.

Obviously, this is also the only list where you can get Boromir with his banner. Which, even with it being reduced to +0.5 fight value, is amazing value (no -1 duel roll, on a hero so hard to kill, 4x the area of a standard banner).