With the new legendaries (both dead man legacy and yang's recurve), the passive is the important part. Having an ancient quiver is not important. You want to have near maximum for the passive, and to have as much as possible :
AS, CC, CDR and multishot damage. And in addition, you need discipline.
So first, Check if you have discipline. Second, check if you have more than 190 multishot damage in the passive. Then check the rest for bonus.
If I understand well, passive for multishot in quiver and bow are multiplicative between themselves.
Thus. Having 200 instead of 164 is:
200/164 = 1.22 => 22% increase in damage.
Unless your other stats in the ancient quiver compensate that loss, you can throw it away.Note that your 15% multishot damage is a separate bonus from the 200, and that alone should give you almost 15% damage increase (depending on how much you have on your helm and boot).