Cooper, I have had good success with it in late January. I have used it on Grays that came in to another sound then spooked for one reason or another, left the scene only to come busting back in, within seconds, when I switched the caller over to the Gray Fox Pup Distress.
Vapredatorhunter used that very method to kill one a couple of nights ago. It came in to Rabbit Distress #1, but spooked and wouldn't commit, so Matt switched over the the Gray Fox Pup for thirty seconds, then right back to the rabbit and bang-flop.
I have nicknamed this sound my "comeback call"