I usually vape at quite low resistances - the coil in my RDA is 0.3ohm - and mix my juice with a fairly high VG content (>70%). I have to drop my nicotine level quite low, otherwise I'll constantly be feeling dizzy and queasy. I currently mix at 4mg, which is double what the TPD will allow, and sometimes I still think that's a little low. Vaping is not nicotine replacement therapy, but that doesn't stop plenty of smokers from taking up vaping in order to get off the fags. 12mg is barely enough for some people who are just making the switch from the stinkies and at 2mg they'll go right back to cigarettes.