I have never purchased a shoe stretcher before but recently needed to stretch out a few pairs that were slightly too small but were priced so low that I couldn't pass them up.  Worked great on these flats and heels.  I love how there are 2 ways to adjust them - you can adjust both the length, and the width!  I don't have bunions but I imagine the attachments for stretching in bunion areas work well, too.
Only thing - can't use them in boots!  the metal things stick out behind the shoe, and there is no place for them to go in a boot.  I am going to have to break them in by walking around the house I suppose.