For an Avenger, that Reapers Toll would have saved your life countless times.
Due to 8/9 FPA, Avengers need some form of CC, be it Confuse, Decrep and/or HF Act2/Cold Act 3 Mercs. Otherwise you may resort to Zeal too much to counter being mobbed.
DS will work on the physical part of your attack with vengeance, but too insignificant for the typical Avenger.
If you have any other source of bonus off-weapon ED like Fort, Fanaticism, Merc's Might aura etc, DS will still work on the physical damage aspect. And helps with leech too.