It is more than just the nic. Switching to PVs takes less effort but, for most of us, it's not effortless. You might find that 18 and 24 mg
juice is too much for you after a while too. I started at 24 and settled on 12. Back when I used cartos, I carried an atomizer and a bottle of higher nic juice. When I'd get a strong craving for something I was missing, I'd do a few drops of the higher nic in the atomizer. I don't use cartos anymore and I can drip in what I do use but, I still have that higher nic juice around. I haven't used it in a while.
One caution, with a cigarette the nic gets to you almost immediately. With a PV, it's a slower build up. If you do what I do with the higher nic, just do a few drops and give it some time. You can get too much while you're waiting.