Frontiers is awesome!
I like a lot the chorus, with Allen answering the choir. Speaking of that, in the last two albums I have missed that kind of "organic" or "real" choir, when all of SX members (or at least P and Romeo) were actually singing. There have been many interesting Choir or Choir-Allen parts in the past (OSaS, Egypt, Communion, Out of The Ashes, Lady of the Snow, DWoT, etc.), but now in PL and Iconoclast the choir is just like "atmospheric", being limited without lyrics and with simple or even one-note melodies (Oculus ex inferni, Revelation, Iconloclast, Heretic, etc.).