I switched to vaping years ago and quit smoking tobacco. As a lead vocalist for the Josh Roy Band, I am overjoyed to report that since that decision took place, my vocal range has increased significantly along with my performances. My vocal endurance has increased significantly. Keep in mind that some e-liquids affect me differently, so do your research on what brands are the safest. 
In addition to the vocal improvement, I no longer wake up coughing my left lung out, no longer have trouble breathing, no longer lack energy and physical endurance has improved. Hope this helps smokers open up their eyes to a new and improved deliverance of nicotine without the harsh effects!