My Multishot Amazon is currently running Windforce Hydra Bow with a total of 90ias (35 from socketed WF and 55 from gear) at the 9fpa BP (no Fanaticism).

My merc is an A2 Might merc with Reaper's Toll.

I am currently thinking about building a Faith bow. I do not want to go the route of putting that on an A1 merc, due to the small aura radius of Fanaticism and the reduced uptime it would give when the merc is not right next to me.

For the bow base I am considering 3 options:

- Grand Matron Bow
- Diamond Bow
- Matriarchal Bow

Also, as I am poor and won't have a 2nd shot at rolling the runeword, I have to assume that I will only roll a lvl 12 Fanaticism aura.

With a Grand Matron Bow and the lowest Fanaticism roll of lvl 12, I would be able to reach the 8fpa BP, but 7fpa is far out of reach (99ias required).
With a Diamond Bow and the lowest Fanaticism roll of lvl 12, I would also only be able to reach the 8fpa BP, making it a worse choice compared to Grand Matron (worse avg dmg and no +bow skills).
With a Matriarchal Bow and the lowest Fanaticism roll of lvl 12, I would be able to reach the 7fpa BP with my current gear (48ias required).

Now comes my question:

Would you rather go for the 7fpa Matriarchal or 8fpa Grand Matron option or ditch the idea entirely and invest elsewhere (e.g. keeping the WF but building a Pride polearm for the merc)?

Buy an already made faith gmb with 15 aura.

Turns out that even with a 15 roll, I won't hit 7fpa with either GMB or Diamond with my 55ias from gear. I could add 10ias from a Nos belt and ditch Razortail, so that I would hit 65ias and reach 7fpa with a Diamond bow. That would then require maxing Pierce on the skilltree. Doesn't appeal to me that much. So my question remains, rather go 8fpa GMB or 7fpa MB?

Those are your main options:
highlords: 20
gloves : 20
3 sockets helm: 45
4 sockets armor: 60

7fps are 3.57 attacks per second
8fps are 3.12 attacks per second

The choice is very simple, do you want 14.4% more attack speed or do you want higher average damage from gmb?
In old d2 we have a better faith with 20ias

Thanks for the APS numbers. That helps with the DPS math:

GMB Faith is 60-309 in a 0% ed base, so the 8fpa dps would be 575,64
MB Faith is 86-202 in a 0% ed base, so the 7fpa dps would be 514,08

So GMB Faith would even win if I only ran 8fpa. Interesting!

My limited 55ias comes from LoH, Cat's Eye and a 30ed/15ias jewel in my Kira's Helm. I'm not going to replace the helm or Fortitude for higher IAS pieces, since I want to run this build with capped res (i know it is an unpopular choice).

If you are hurt with bowa then you should use more decoy. I 100% would change kira.
What armor are you using now?

I’m new to bowazon. But as I understand it, any +max/min dmg (from charms, maybe jewels) will add directly into the damage range of the 2 weapons you are considering, making the damage difference between them smaller in % terms.

You might also want to consider the ease of maintaining these respective 7fps and 8fps should you need to swap out gears (eg you might prefer atlas scarab in certain situations), and maybe even replace the jewels you socket to max+ED if you don’t need the ias

Fort

That's a good point. I'll sum up my min and max values later and redo the DPS calc with that.

Gmb faith 15
Forti
Nos belt
120/45/30frw helm
Loh
Raven
Dual leech ring
Wts
Highlord

Standard bowa build.