I've recounted this before, but it bears repeating here.
A few weeks ago, I went to see my neurologist, who I see more than my PCP. I told him that I had quit smoking and started vaping again. I showed him my mobile setup, and he thought it looked strange (a 18350 IMO with a KOOL tank). He told me that he would rather see me do that than smoke. He knows what a demon nicotine addiction is to people with Parkinson's. It gives you a mild, very short term relief, so the addiction is really quite severe.
He recounted to me a lunch that he had recently had with the pulmonologists (sp?) (he's the asst Chief of Staff at the hospital he's affiliated with). At some point, he asked about vaping, given how many of his patients were smokers. To a man, they told him that they'd rather deal with any ill effects from vaping than with the known horrors of long term tobacco use. None of them had ever encountered any problems related to vaping.
Bottom line, he said that he thought it was a good trade off. Of course, he'd rather I gave up nicotine altogether, but he understands the wicked hold of the addiction.