Oxycontin is likely a safer drug than heroin. That doesn't mean we should be working on growing the Oxycontin market on the assumption that every new user is someone who might have otherwise used heroin.
I am not aware of any doctors that would recommend using methadone permanently and and it is only legally available to be prescribed for ongoing substitution therapy by federally certified abuse recovery centers. So my analogy still stands. No one should be actively campaigning to grow the methadone market the way that people are for e-cigarettes.
As far as I remember you are getting cancer, although at a lower risk, at least accordingly to some study posted here in the past that I can’t pinpoint right now.
If being addicted to Oxy was 95-99% less harmful than being addicted to heroin, I think we'd be OK with a small rise in Oxy users as heroin use fell off.
But as these are not in any way analagous to the current situation, it seems silly to talk about them.
Either way, the bulk of health damage from smoking was from the complimentary products of burning. You ain't getting lung cancer from nicotine.