Lightning and fire dmg through projectiles : projectile weakness or elemental weakness ?

I have a LA ranger that is starting to be self-viable (mostly because the graphic have improve and I get less lag and crashes).

Yesterday I bought a berek's respite. So I modified some of my char. And I though it was the time to have another curse (I've been using temporal chains since now, to survive).

So LA+blackgleam = 50% lightning dmg + 50% fire dmg. But it's projectile...

So, which curse will be the most efficient in terms of dps ? Projectile weakness or elemental weakness ?

projectile weakness will give you around 50% more damage(34%more + going to assume some 10% more accuracy) + 60% pierce against all enemies which can be massive increase in dps against large packs

while elemental weakness will give you more damage boost depending on how hard the monster is to kill. monster with 50% resist with -49% from ele weakness = 100% more damage. and monster with 0 resist = 50% more damage.

I had a similar choice when deciding on Proj. weakness vs Frostbite. Frostbite won, mainly due to freeze chance being an important part of my playstyle. I think damage-wise it was a pretty close call, except against high resist mobs in which case Frostbite was definitely a win.

The only other curse you might consider is Critical Weakness, but ONLY IF you're considering incorporating critical strike into your build. If you are not, then also take a look near the bottom of this page to learn a bit about resistances: http://pathofexile.gamepedia.com/Resistances

Do note that if you go with Projectile Weakness you probably will not want to augment LA with Chain/Fork because the piercing chance will override those. Putting it very simply.

1. If a projectile can Pierce and it rolls the pierce chance, then Fork/Chain will not occur.
2. If a projectile can Fork, then it will never Chain.
3. If a projectile can Chain, then it will Chain.

Therefore the order of priority is: Pierce > Fork > Chain

Thanks for your answers !

Yes, my LA is supporter by Chain (with LoH, WED, LMP). And I don't need accuracy since I use a Lioneyes'...

So i've tried Projectile weakness (mostly because of the available green socket), and I must say that it's insane ! Especially on single target (Frenzy, so only 50% dmg is fire, the other 50% is physical).

Maybe I should simply get rid of Temporal Chain, and use Projectile weakness on single target, and elemental weakness on mob pack ?