Thank you very much! 
I would say crate boss is not so bad for some meeles with necromancer or arcanist support like battlemages/spellbinders/deathknights (mot or mirror op) but harder for sure than with aoe bombers/pets/retaliations. Wasn’t very hard, I died once with DW setup because I wanted to speedrun him, at something like ~1:20 time I failed on 1% health 
I took RE because I am more used to it, I feel more comfortable with insta dr before spreading omen but it’s probably more like personal preference.