Reaper and Immortal sacrifice

[Petite]

But my main point here is that reaper is pretty good, and fun to play, but losing all stacks of immortal sacrifice on death really hurts.

It doesn't "really hurt" though. Plentiful Harvest is a "fire and forget" skill you press on cooldown to get to your LB ASAP. If you manage to gain anything from it, it's usually by circumstantial luck. Compared with Crest, Hell's Ingress and LB, RPR barely relies on PH to be effective.