It does in practice. You require a single um rune with cure to have resists maxed. That's my go to combo with my blizzard sorc.
well I was considering the uber jewel armor setups. If you use an um in skin of the flayed one, then compared to COH you get a bit more defense (2061 flayed vs 1380 coh vs 720 greyform) but lose big amounts of damage and leech (not just the 1%, but also the extra dps for more leech), on top of the less important % dr / mf / aura to player. The upside of the protector's stone setup is to get that fade in longer games, so without the jewel not much reason to use the armors with sockets, even a 15/15 jewel just makes the difference of 6.5->6 fpa anyway
Budget:
Skin of flayed one + um
High end:
Coh
Coh is just more reliable.
The main thing you need from your merc is reliability and increasing the support he brings, which is slightly increased by the +2 skill.
I appreciate the effort to theorycraft around all this, but I really don’t see it outclassing the above. And that jewel is not budget, so it falls at an awkward spot for a merc.
Again, I feel like it’s worth it in arioc/reaper on a barb who would really benefit from this investment as his slower kill speed leaves more room to the merc to deal dmg. But that’s about it…
Considering the best in slot rather than budget.
The thing is that all the affixes on COH other than 8% leech are kind of meh, to the point even a unique a1 norm quilted armor you find off coldcrow can compete
As per the example before, we're talking some extra DPS in most cases and a significant leech advantage for COH- but stone on its own recouping a considering portion of that deficit, and gets 1% of fade as its main draw. Stone setup should deal more DPS to most animals and might deal about the same to undead or a little less, COH will deal more to demons and leech more in all the scenarios.