I have been using the Grendel since 2016. Shot 4 Antelope, half a dozen pigs one doe one Aoudad ewe and one big hairy Aoudad ram. All with Hornady 123 gr SST.
A dozen animals isn't quite conclusive, on most of these critters, I was 200 or under. All my shots were quickly effective. Maybe 3 of them took more than a couple steps. Most fell DRT when I shot well. Even the Doodad. Pigs were shot in the neck, shoulder on all Antelope and doe and frontal chest on Aoudad.
I am very impressed with this round. I wouldn't hesitate to recommend it for anything under (but not quite including) Elk.