Ive used the pump yelper and mouth yelper since they came out and they do work,,,,,,,sometimes. I drew in a gobbler the year before last that hung up on me 100 yards out in field. This bird wouldnt respond to any of my other calls, ( slate, aluminum, box, or pushbutton. But as soon as I hit the pump yelper it went nuts. Guess it never heard one before. I have used the pump yelper to shock gobble alot of birds. Seems to work good that way. However, I usually switch to my slate after I get an initial response . Thats the only time I have had much luck with it.
I like the mouth yelper in conjunction with my gun mounted call to bring them in that last few yards.
For a person who wants a good, all around, consistant call... Id say NO to these two. However, I will always carry mine with me in case the birds dont respond to anything else. [:-]