I tried both the Haint and the Hale Fire... Like the sound of the Hale Fire better (from my recollection)... Ended up digging through some really old call of my Grandfather and found an old predator or squirrel call that sounds even better (blown with the same method).
These calls are relatively easy for duck hunters to master... You have to use a feeding call in combination with the correct back pressure (cupping your hands over the end of the call properly), while blowing from your diaphragm (NOT your mouth). It seems consistently difficult for non-duck hunters to master.
I would say that a good gobble call has lead to increased success in multiple instances for me... All too often in quiet woods, I will blow a gobble call, pause, and then a hen yelp... I think that very often gobbling is contagious among turkeys, and that hearing another bird winds them up a bit.
I have also used a gobble call on henned up birds (in conjunction with a hen yelp)... That invading bird with a hen, sometimes sparks that gobbler to come in lookin' for a fight to defend his territory.
I do believe there are also times when it has put birds off...
