@Ringeling If a cis dude's physical appearance is changed so much that they fit the shemale tag better than male crossdresser, than it should be counted as gender bender.
@Ringeling As "The Goat is Watching" poorly explained (with incorrect/exploitative terms), "gender bender" is an older term that was semi-/fairly correctly. That is, it foremost refers to appearance, secondary physical characteristics, and personality/psychological changes, thought not always; but also, is used for what you were thinking of, sex/genital transformations.