fem.seed hermie ratio

hello everybody, I have only ever grown from regular seeds fearful of the thought of femenized beans going hermie on me. from your personal experience how many hermie's (if any) have you ended up with and was is caused by stress or did it occur naturally. I ask because I have noticed alot of the big companys switching to feminized seeds only so i figure i'll have to make the switch at some point but would like to know other peoples thoughts on fem. seeds. I have done plenty of research and understand fem. seeds are created using hermies so they are not considered to be stable, if i'm only gonna end up with 1 hermie out of 20 seeds I can deal with that but i've heard storys and read storys on here of entire packs of seeds growing bananas.

please post your thoughts on this subject and try to keep all comments constructive please