So basically soul rending gives metamorphosis 50% leech, Demon form grants 45% max hp (at least if you have artifact trait bonus it might go as high as 50%-60%) and 100% armor . And on top of that each shear grants a soul fragment which makes their self heal even more insane. Let me show you some stats :
A 890 ilvl DH with metamorphosis can have 6.6 million hp, 11k armor (40% more than bears in their default armor without IF stacks ofcourse) and crazy self heals. Having that in mind do you think we should still pick soul rending or we can use other talent? Would it be an overkill if we go for soul rending as meta is currently so tough already. There is no other class in the game with such a powerful cooldown at the moment. I really like that... The only way of killing that in pvp is kiting and nothing else.