I haven't had time to read the whole thread to this point, but just to weigh in on dual use - I did it for a month or so, and tapered during that time from 15-20 a day to 5 or less. Wife finally pushed me to quit by just saying something along the lines of "We're going for it - tomorrow."
Since the banner start date in my sig I've had one or two - most recently last July 4, when I lit up my trusty Marlboro Light 100, got about halfway through it, and stubbed the .... and grabbed my Ego instead. A couple months later I gave the last 4-5 cigs that had been sitting in that pack as a kind of 'safety blanket' to a smoker buddy who'd come over to hang out and ran out of smokes. Haven't looked back since. My wife likewise had a couple relapses in the first few months, but after a cig (or half a cig) put them back down for the vape.
No hate for the people who either choose to still smoke or feel like they have to smoke still - if you decide to quit one day, right on. If not, just count the ones you're not smoking and be happy with that - you deserve to.