Counter attack gem applications

So what application do you find for vengeance / riposte / reckoning ?
I looted one and wondering ...

-extra damage - attack once per 1.2s is not exactly much when attack speed is one of major dps factors - But i guess it does promote usage of slower weapon over fast ones (that have bigger benefit from +flat damage). shame multistrike doesn't work with it.

- suplementing your life/mana leech - mostly for leveling when you don't have links/gear to get proper leech

- curse on hit (assuming it works) - CWDT is better at this regard unless you need high level curse

- Blind - same as above

- cast on melee kill - what sort of spell you would want to trigger?

Vengeance + culling strike + item rarity + item quantity

Some extra loots, take out quantity if you play temp leagues

I have Vengeance and Reckoning on my Daresso's Courage (120% increased Block Recovery) shield on my Facebreaker build. At least for lower level content (A3M Lunaris), the counters are powerful enough to one-shot trash mobs without needing additional supports other than Melee Physical Damage.

Decent utility, for not much investment in terms of slots occupied.

Riposte is the only 1.3 gem that I haven't managed to loot yet, so haven't had any experience with it to see whether it's usable with Facebreaker.

Does anyone know if I have multiples of, say, Vengeance gems, will they proc separately?
Like if I have:
Vengeance-Cast on Melee Kill-Immortal Call
Vengeance-Vengeance-Blind-Increased AoE
Vengeance-Vengeance-Vengeance-Vengeance-Vengeance-Vengeance
When I get hit, will all 9 of those vengeance gems roll for their 30% chance, and then (probably at least one, but RNG) procs?
Or will the game only roll for like....the highest leveled vengeance? the highest quality vengeance?

(On that note, I assume ranged attacks can still trigger these gems? Or is 'melee hit' assumed?)

@Milchut
I think the cooldown is on skill not gem (much like CWDT and EC)) so only one will trigger - no idea whatever it would be at random , by order or only one will keep procing while rest will never activate.

When it comes for proc on vengeance - ranged melee and spells work.

Oh well yeah, I figured the cooldown would happen regardless, but I could potentially fake a really high proc chance with using multiple gems.
Might not be worth it but could be fun to mess with.

I currently have ECoMS linked to Vengeance, not to generate charges, but to set the timer back to 10s.

Vengeance-Reckoning-Leech-Life Gain on Hit

Never die to screen freeze again.

I have been testing vengeance on crit and it works well to get leech bursts, but it still does not solve the main melee problem : Taking the big first hit.

Melee is still in disadvante even with the introduction of these gems. If you get a big hit of 6K-8K, you will die to it and there is nothing can save you.

No leech by high DPS, Inmortal Call or armour will ever save you of that. So yeah, melee is still being shit by ranged.

My idea was: Counter Gem - Cast on Melee Kill - Detonate Dead - Endurance Charge on Melee Stun

This coupled with: Cast when Stunned - Molten Shell - Immortal Call - Lightning Warp