In summary-- I got an Oni Ed, and a Gunner Minotaur. Plus 89 skill shards.

Believe it or not-- I pulled Gunner Minotaur from a stack of 10 "rare gunner/assassin" souls

Sacrificed 567,645 essence. 6 Vortex, 4 Ultimate, and 18 Exalted. I'm down 8mil gold, but up 800+ Ironite. Earned 4980 Snow frags.

...

OBSERVATION: Ten 4* level 1 G/A souls = 20,250. Nine 4* level 1 W/M/S souls + a level 100 Ultimate Heart = 20,200.
Sacrificial Hearts may not be a "good value" for leveling up, BUT their level 100 essence is designed to fill up Exalted Sacrifices.