I am using 6mg, at the moment, however I do have to vape almost continuously to keep my nic levels up. I am not used to the peaks and valleys, since I usually had a pinch of snuff in my lip all day long.
I switched to vaping due to the deterioration of my gums/teeth, breath, stomach issues from swallowing tobacco for so long (heartburn and reflux), and lastly to just get rid of the ick factor.