The usefulness of this chip or any method of such feedback would be
learning to be more attractive. While incredible to control one's genes
right now, it is credible to control one's memes. A lot of attractive
persons are distinguished by behaviorial traits (smiles, tilt of the head,
regular exercise, hygiene, fashion). While not all is memetically
controllable, it is enough to bother with if you desire to be desired.
Though for less than the price of implementing the chip system it might be
possible to learn subtle signs of hormonal raise through another's
responses to your presence. It would not be as accurate for the hormones,
but developing a buddhist like mindfulness of the other person's state may
allow you some useful information (which may be more honest than asking the
person how e reacts to you.)