So when you resize (using the "Same Width" "Same Height" or "Same Size" option on the [Arrange] ribbon).. the application resizes all callouts selected according to the overall size of the primary callout (this includes the length of any attached arrow).
Unlike the process of resizing text boxes (which works fine).. you simply cannot get the comment boxes on callouts to be the same size. Callout comment boxes get squeezed, or stretched at random - because the arrow length is included in the Width and Height size - the length of arrow on each callout is 99.999% going to be unique, so the process of resizing callouts will drive you nuts. you simply cannot get the comment box on the callouts to be the same size!...

Am I missing something, is there a way to resize all comment boxes of your callouts (to be the same), and leave the arrow lengths out of the equation?