I had a friend who's e-cigarette turned into a flame thrower about 5 minutes after he plugged it into his laptop to recharge. The lithium battery holds charge far longer than other batteries. People who over charge tend to catch their house on fire.
Also, ecigarettes contain propylene glycol. Which is toxic.
But if you're smoking you're already poisoning yourself. And if you're using nicotine patches you're ingesting the dermal chemical of nicotine. So you're still getting your "nic" fix.
You can't open e-cigarettes and put marijuana in them. That's a myth.
There's another kind that you most certainly can. It doesn't look like a cigarette with a glowing tip. It looks like, for lack of a better term, a bong, or a hookah. In some places, there are bars popping up where you take your, ahem, device, and pay for them to load it with a flavored nicotine dosage. So yes, you can switch that with liquid THC. But this is a digression.
Here's my point. If you smoke, and you want to quit, part of that is detaching from the nicotine, part of it is detaching from the ritual. I know, because I was doing it for 40 years. Nicotine is a mood-altering drug, a mild one, but over time, you require more and more to get the same effect, just like heroin. It's true that most of the harm to you comes from the other agents in cigarette smoke, and by eliminating the smoke, you're only using nicotine. So, in my opinion, if you use a nicotine gum, patch or ecig to help you quit smoking, it's like using beer to get off of alcohol.
The other point is our dependency, as a society, on mood-altering. Whether you're addicted to porn, booze, drugs, or sex, or any other addiction, we have a problem with dependency in our world today.
To say "Hey, at least he's not smoking!" is sorta like if your kid wants to go to a movie, and tries to sell it to you by saying that there's only a little sex and foul language, so can I go???" I heard a guy answer this question this way..."What if I told you we were going to have a pizza party, and that you could eat as much as you want. There's dog droppings in the dough. Only a little. Let's eat!" Kid got the point.
I understand that people want to feel good. Everyone has their crutch. Some folks, it's food, whether fast food or fatty food, some it's alcohol, and hey! I have mine. I like wine. Most days I limit myself to a glass with dinner. Some days I want a little more. But I've also gone the entire 40 days of Lent without drinking a drop. The point is to determine who's the master of your body. You, or the nicotine. You, or the wine. You, or the steak. Self-denial is the best way to get it. I've also heard people say "If you're going to give that up, and you're going to be grumpy all the time, I don't want any part of you." Those folks might do better with a step-down system. I guess. When I quit smoking, I didn't even tell my wife (I wasn't allowed to smoke in the house or car, thanks. Only at work). Because so many times I had failed. This time, I just did it, and told her after about 2 months.