IMO Frozen Banshee was better than all of those before (except Occult Brawler). I have a 60 FB and 60 Occult Brawler both geared up and before this patch they were both pretty close in damage.
With my Occult Brawler with the extra turn mastery (Master Hexer) for debuffs I could stack as many as 8 poisons on a target at once.... which came out to 500,000 damage per round. It would take 6 rounds to be able to get enough 5 turn and 3 turn procs to get there. But the problem became that poisons would crowd out the possibility of other debuffs.... which I would argue the later you go down clan boss the more you need to weaken the clan boss.
The other big problem with Occult Brawler is that he doesn't provide a crazy amount of utility. With the way he works you only use his A2 if he has five stacks of debuffs on him (for an extra turn). So he basically only adds poison and will always crowd out debuffs. It also means someone like Grizzled Jarl doesn't have good synergy because he's going to prevent debuffs from happening.
Banshee provides two poisons per turn which are 25% stronger. I tried putting both OB and Banshee on the same team. It resulted in silly damage for OB but overall lower damage for the run because it didn't last as long due to a lack of debuffing. But interestingly enough her chance to hit isn't dependent on accuracy at all so you can pump her full of speed (she has an 80% chance to apply poison naturally vs 50% for OB).
But her poisons are only two turns. So with a 30% chance of getting an extra turn on a debuff from the Hexer mastery. That means at best she will be able to rotate 5 poisons. But since they're stronger they'll act like 6.5 poisons.
So what you lose from the change is a single 1.5 5% poisons (on perfect RNG situations). What you gain is a turn booster and one extra space for a debuff. In my setup I have Grizzled Jarl and Rhazin Scarhide who provide my debuffs, but Banshee is a perfect fit for me, but maybe you have less debuffers and maybe then OB would be better for you.
But if you have more debuffers Erinyes will give you more space for them. Erinyes does really well if the rest of your team is solid. She has enough utility to bump up the rest of your team on top of adding some poisons.