There isn't enough longitudinal data yet to really say, so I'm going to just say that you'll have to decide based on what research there IS available now, which seems to (for the most part, with some exceptions) indicate vaping is safer than smoking for the most part. I don't have COPD but I was headed there, and my lung function has greatly improved. I've heard of new vapers with COPD finding improvement in their sx when they switched to vaping. Mouth cancer, IDK? It seems to me that most studies are finding that it isn't inhalation of nic that causes problems, but rather combustion and tar. With that said, that doesn't mean a former smoker won't wind up with cancer at some point, and it would be hard to tease out whether or not that was caused by (former) smoking, vaping, or what. Nicotine is safer than smoking, overall, but there are some risks (mainly vascular and cardio risks) from nicotine, but they seem to be less than those combining nicotine *and* tobacco, again, due to tar and combustion.
However, I do try to be mindful about how much I'm vaping, I prefer MTL vaping and less vapor per day, though there are certainly times I chainvape (mainly in the a.m.) I don't think anyone can tell you that vaping is *safe* but it does seem to be safer than *smoking.* To eliminate all risk the safest thing to do is to neither smoke nor vape. This may be something you want to take up with your doctor? I try my best to limit my exposure to too much flavoring, too much vape, generally (this means I am avoiding sub0hm setups). The nic is the least of my worries, but I told myself that IF I could get to stable vaping, I wouldn't fret about the nic, though I may reduce it over the weekend, I am thinking.
I can't say whether vaping is *safe* for you-- only you can make that decision possibly with the input of your doc, if they aren't rabidly anti-vaping and could work out a treatment plan for you-- for example if you are worried about your lung health you could get a cat scan which would give your doc a pretty accurate picture of what's going on in there. You could do a flowmeter test to measure your lung health every 6 months to a year, to see if your lung health is improving or getting worse. You could get an EKG and even a echocardiogram to check the state of your heart, etc. If your doc is willing to order these test for you, you will have a baseline that you could periodically update.
My docs are very happy I am vaping, but I have only seen health improvements, personally. One of my doctors vapes and he is excellent to talk to about vaping. He feels it's unlikely to cause lung damage unless you are finding one of your vape ingredients to be an irritant. He does state that cardiovascular and the cardiac system generally *can* be impacted by vaping, but states no one really knows at this point how much.
But, those are the things YOU can do. If you are worried about your intake of e-juice, you could use a less powerful setup and/or find ways to vape less.
Best of luck,
Anna