I'd just address the bigger issue: if he was vaping behind your back to "be cool" - what's next? I would not be happy, and would definitely NOT support it just because of the "sneaky" aspect of it.
Just me. You can do as you like, of course.
I agree with this. Certainly 99% of people who are involved in the community were former or soon-to-be former smokers - adults who made conscious choices to quit smoking and use the best tool available, I would even say mostly responsible and friendly people. It is easy to say that this is very much harmless compared to cigarettes and other substances, but the societal impact and youth reception haven't really been examined because it simply hasn't been around long enough.
I don't imagine kids even wanting to smoke after trying the e-cig, but I can say at least this: the e-cig community is probably the happiest, most friendly, most helpful, and most supportive group of people in America and potentially the world. People want to live a healthier life, and we generally help each other get there.
If your son does get into it more, he will have the opportunity to meet and network with some great friendly people. The differences between e-cigarettes and regular cigarettes go far beyond tobacco and vapor