ive never actually been made to change out the insides yet aside from one time due to user error lol, as for dry hits i havent really experienced any with the standard size
tank, now with my xl i get dry hits when the tank gets fairly low just tilt a little and wait a couple seconds and you are good to go again. my user error on the standard size was trying to move the wick over to try and get "new" wick into the coils which caused the coil to break, otherwise ive had no problems, when i first get the replacements i like to "burn" them with a pocket torch i notice that it seems to give better flavor for me but that may be all in my head lol but even right out of the package it works beautifully.