When you do the math for the poison mechanic on SRS - Poison is one of the better support gems for single target.
While Multistrike is better if you scale SRS with things like Wrath, Anger and flat damage support gems Poison will be better on an Hatred/Phys damage scaling SRS build nowadays.
It is easy to say that when you are playing in an party with an aura bot, "Elemental SRS" with Multistrike will be best clear speed over all due to the fact the 70% damage effectivness modifier got removed from the gem.
When you are a solo player you normaly don't run that many 50% auras by yourself. "Physical/Conversion" SRS with Melee Physical and Hatred has a lot more physical DPS on hit than the Multistrike build so that the Poison support gem becomes relevent.
Poison won't do much in terms of generel clear speed in maps against normal monster packs and champions - monsters die in split seconds anyways even i high maps with good gear. Against high HP high resist rare monsters it can make a difference of a few seconds with or without poison.
Where poison really shines is against strong unique bosses, like Atziri/Vaal/Trio, Dominus, Voll, Malachai, Piety, Daresso, Kaom etc.
In fact: The higher the effective HP of the boss you face is the more effevtive Poison will be against him when used with SRS. Against those bosses you usually ramp up before hand with an SRS build and get 40+ spirits out, turn on Vaal Haste and after that you start the boss encounter.
Since stacking poison has no limit other than duration you can get 150+ stacks easily on a boss, which is insane due to scaling with minion damage modifiers.
I've being playing srs for first time in breach and I have no issues so far, can do every boss, every map mode, to me this build is still very strong.
I don't think there any need in using poison support because of the new sword '' United in dream '' which is also way cheaper than a +3 bow bow ( I did try both during the league )
my gear so far in breach
of course at this point I have godly item, but it's mostly because I've being able to clearspeed kill boss like atziri and guardian very early and fairly easy.
I've being playing srs for first time in breach and I have no issues so far, can do every boss, every map mode, to me this build is still very strong.
I don't think there any need in using poison support because of the new sword '' United in dream '' which is also way cheaper than a +3 bow bow ( I did try both during the league )
my gear so far in breach
of course at this point I have godly item, but it's mostly because I've being able to clearspeed kill boss like atziri and guardian very early and fairly easy.
I see a lot of people doing poison SRS with added chaos and void manip.
I get the void manip and added chaos. but I don't get the removal of physical damage. a 50% increase in melee damage (which also applies poison) Should be favorable over culling strike. Would you also consider running a lv 4 Empower?