Concentration vs Fanaticism amd other warlock's merc woes

Background
Pure summoner warlock, teleporting with the throw weapon thingy, one point in Lethargy. Ran all of Norm/Nm/Hell with Act 1 merc with

Edge Bow for

Thorns. She's great.

Started using Hell Lister, which is great, but clear is slow. Note: I don't care about insta-deleting screens, but it gets dull recasting lethargy below uniques and bosses for 2-3 min.

So, I switched to Act 2 Merc with might after getting a unique

Thresher that procs

Decrepify. Damage and clear is definitely better, but Act 2 merc is a pain to keep alive. I spent some resources and kitted him with

Guardian Angel and Kira's for max resists. Still squishy, so at this point he's great until he dies, after which I would have been better off with my Act 1 merc and

Thorns.

Fast Forward
I managed to bind a cursed Lister! But it got

Blessed Aim... Still, the Amp Dam curse really helps clear. I love it. I'm sad, sad, sad they are nerfing it (what else do summoners even have? Goats are sooo slow). Then I got a cursed Lister with

Holy Freeze and that is amazeballs.

BUT, now I don't want my Act 2 merc overwriting Amp with Decrep and there's still the squishy problem.

Solutions
1. I can go back to Rogue and give her Faith for

Fanaticism or Mist for

Concentration.. but which one is better? And what do I

Sacrifice by losing Might from Act 2 merc?
2. Briefly toyed with the idea of giving a rogue Bramble and Edge for a lvl 30-36

Thorns. But is that any good in Hell?
3. I can give the might merc a Pride to have both Might and

Concentration. To my knowledge, I can't get the Act 2 merc to have both Might and

Fanaticism.
4. I can try to make the Act 2 merc less squishy. Is there a better chest/

Helm combo that will protect them? Fortitude? Andy or Vamp Gaze over Kira?
5. I can try to reroll a Lister with Cursed/

Fanaticism, but I might prefer to gouge my eyes out. Note: I've been getting Listers from

Baal runs to take advantage of the increased health (and power?) of P8, which is of course a challenge.
5. I am also testing an Act 5 merc with

Dreadfang for the dreaded Amp Dam nerf to compensate for loss of regular

Amplify Damage. Guess we'll see what happens with the patch.

Mostly, I would love to go back to Rogue merc, but worried I need some combo of Might +

Concentration/

Fanaticism to keep clear up. Any thoughts? If I had to choose between

Fanaticism or

Concentration (i.e., Faith vs. Mist), what would you choose?

Thanks!

Did u say bosses take u 2-3 mins? What is your setup exactly? I'm using

Holy Shock/cursed lister w 2 defilers, switch to 2 goatmen for bosses and diablo/

Baal take a few seconds. I'm not using

Blood Boil or

Consume, just max

Bind Demon,

Blood Oath,

Demonic Mastery,

Death Mark for

Goatman cb%. I'm using cold rogue merc for cc, w Harmony for mobility, Treachery, and

Guillaume's Face just to speed up boss kills. It's not huge but she's like a 3rd

Goatman, and she never takes damage behind my summons so i don't bother to gear her for better survivability. Absolutely love the

Vigor aura from Harmony and could not live without it if i switched to a2 merc
I'm using

Ondal's Wisdom +

Ars Tor'Baalos, and the rest of my gear is into magic find and run/walk speed. I maybe spent like 4

Ist gearing him, certainly nothing like Faith or Pride or anything. And even with random non-cursed bound demons with like, might aura i find my clear speed in dense areas barely slows down - bosses take about twice as long but still well under a minute
Would be really curious to hear more about ur skills etc