Mathematically with the maelstrom bow Arrow Barrage and Endless Hail are very, very close. (I would say probably indistinguishable in most practical situations.) Arrow Barrage does more damage than Hail without the maelstrom bow, and it has a wider radius. It also fits into rotations more smoothly at a 10-second rather than 14-second duration (effectively). But it does take a little more sustain, as you’re looking at roughly three casts of Barrage in the space of two Hails.