*reads the Codex entry about the Rachni War* Yes.
Be fair, that's not a good example since those aren't Rachni, but Rachni that were huskified by the Reapers. The husk version of races are stronger than the race they are made from. Add to that that there were a lot of them vs one Grunt, while we're talking a duel.
A Brood Warrior would only come out to face Grunt after Grunt killed practically all the other Rachni of a colony. 
Didn't expect a conversation to come of this, so we should probably get back ontopic.
Ah yes the Rachni Wars, a 300 year grueling slugfest that was defeated by the combined efforts of the Salarians, Asari, and Krogan. Even if we give the battle toads all the credit; they joined the fighting after the Rachni had been invading for almost 100 years, and it took them 200 to push them back and win. Meanwhile, the Krogan Rebellions could barely last more than a few decades, before they were pushed back to their nuclear hellhole of a homeworld. 
And I am being fair,
Ravengers are horrible at close to medium range, Grunt would have been flayed alive if he tried that same stunt against actual Rachni with their armor piercing claws.
Plus if we are talking about a hypothetical one on one fight then a Rachni Brood Warrior vs. Grunt would't go in Steve Blum's favor. An alien with natural weapons on par with modern day armor, and a skin that is bullet resistant, not to mention the biotic abilities and acid spit it can bring to the fight. 
But I do agree, we should get back on topic:
No Cerberus, not now, not ever.