Let me add my congratulations to the top of the pile, and say "Good work, Dad!
And to answer your original question, I think you ought to record him and give it a try! If it doesn't call them in, I'll always think it should have.
Several years back, my younger brother was camping in Montana and had to change a diaper in the middle of the night. The kid let out a holler and the coyotes lit up all around him. I'm not sure whether they thought it was a distress cry, a little coyote howling, or were just reacting like to a siren. The way his kid screamed it could be any of those. 
Of course I wouldn't play that particular sound too close to habitation, you might call in all sorts of upset two legged female type varmints. I wouldn't let the wife catch me with that tape either...
