Vengeance:
I agree with you on Draining Scream and Eviscerate, they do feel undertuned right now. When you first have access to the talents they are amazing, but as you get so high up not so much. Calling them a DPS loss is over dramatizing it a bit, as there are no other DPS increases you can take and still get Shatter.
I'd suggest the easy path of allowing the bleeds in scale more in-line.
Also by the way the timing of abilities goes - rework the separate bleeds into one bleed that increases the total damage of the bleed done as more bleeds are applied. So if you Shatter -> Scream, the bleed gets refreshed and maximum damage over time goes from 1325~ to 1600~. If you impale on top of that refreshes the dot and -> ~2000 and so on, so on. There would be major balance issues if this was implemented in pvp, I'd imagine.
For Huddle I can think of a few fixes.
Obvious fix is to move into immortal. But I'd recommend swapping the charge stun effect with the intercede fix, that seems the most logical trade to me. And on top of that, you could make the ability shallower as well, but even this will have some issues and so on.
I know nothing about the rage tree, so i can't comment.
Immortal Tree...
My only issue with immortal currently is Sonic Barrier. Sonic Barrier feels very weak approaching max level. I think it comes out to about a roughly 500 damage shield. It definitely needs to be scaled unless the idea was to only absorb a 1/4~1/2 hit from a mob. No idea if it scales with shield absorb, but it would be nice if it did.