Molten Strike Question

Hello there, im using PoE


I play a poison Molten Strike Pathfinder and wanted to optimize my DPS for Magma Balls.
When i check support skills in PoB with Full DPS i get this:

Chance to poison: +107%
Greater multiple projectile support: -0,9%
But when i check PoENinja, 77% use GmP, only 0,7% use CtP.

Can someone explain this discrepancy?
Is it right to assume the more projectiles help with clearing only?


Edit:
After playing a few maps i cant say that i notice a difference.
Neither on clearing speed nor boss damage.

Edit 2:
I now have 100% chance to poison due to

But CtP still gives me +23%
Best in slot according to PoB would be now Added Cold Damage with +32%

Found this MS Simulator

https://moldydwarf.gitlab.io/MoltenStrikeDPS/moltenstrike-simple.html#zip_eJyrVirIT3JKzMlxyU1XsjI0AAEdmJhHZolzRmJecipYBizsm5qTmoquFizoWFAMEkQIYNEdkOSSWVyiZJVXmpMDFfDPU7IqKSpNBXPdEouCM/JLQGJpiTnFEEG/0lyQYxCmg3hBiSmZpUAhS4h9iRVgPwANh1hoZKqjlJRfXAxTZlQLAPiYS/M=

According to this the 4 more GMP projectiles increases my DPS by ~30%.
So i guess its a PoB thing as so often or i missed something in the Config.