I used to be in that racket years ago. Although I can't speak to every L.I. company, I can tell you that they are all ultra-conservative when it comes to risks and won't give a vaper a NS rate unless you're looking for a massive policy that would justify the costs involved in deviating from their standard underwriting procedures. Until there is enough data to prove a reduced mortality of vapers vs. smokers, they will continue to rate them the same. In 30 years or so, assuming someone does the epidemiological studies, there may be enough data to prove to their satisfaction that they incur a lesser risk by insuring the life of a vaper. Until then, don't hold your breath. They won't change rates on intuition, anecdotal information or medical consensus. Numbers, actuaries and bean counters rule that industry.
If there is one company that will possibly, just maybe, break the mold, it is a company, sold by independent agents, called Jackson National L.I. Co.. They're super solid financially and I used to use them for hard to place risks. Their underwriters would take a lot of accounts on a case-by-case basis instead of working off hard and fast rules.
The problem is, there might be a way to distinguish between a smoker and a vaper. But it is unlikely to be cheap and convenient enough for their cookie-cutter underwriting. So, they'd rather not fool with it and there is no other cheap way besides nic. level to prove to them you don't smoke, even if they cared. And they don't.