As I understand this, you work at this pet shop and you are leaning toward the female. I am assuming then that you have the ability to spend some time with this little lady and therefore see if she likes you also. Perhaps you could take this grey home and see if you two are compatible and see if the plucking lessens. Frankly I find that if you want a certain pet you know so almost instantly so if you have any doubts, I would just not choose neither and pass until I find the grey I really want. Greys live a long time so, I would want to be certain that I am giving a re-homed grey final forever home.