I've been running 531 for 11 months now, just wrapping up cycle #10. No signs of stalling yet. I have spent a good decade on a bro bullshite split, and a year directly before on a more sensible strength program.
My squat and bench were pretty low to begin with before I started 531, though. Nevertheless, squat went from 240lbs to about 380lbs, bench from around 175lbs to 225lbs, and deadlift from 400lbs to around 500lbs.
The big irony of it is that I made substantial mass gains as well ever since focusing on strength (as opposed to focusing on mass during the bro split days). Also did start eating like a man, though.