Great advise. I think I will follow it too.
as some one mentioned, even kanger 1.8 coils do not read 1.8 all the time either.
from personal experience - when i put a fresh coil in, il have the mvp read it so i know what the "base value" was before i used it. after a few days or a week of use(depends on situation) il keep checking the resistance. once it goes up .2 i change it. tho i can say, i should change coils more frequently.