I quit smoking not only because of the health risks (even before HRT), but because it is about the least feminine thing a person can do. It's gross, it stinks, it gives you horrible breath, it makes your clothes stink, it makes your hair stink, it makes your car stink, your house stink, etc. Oh and it ruins your makeup.
For MtF's, if passing is a priority, then kicking the habit is probably a really good step in the right direction in that regards.
-AM