I don't subohm at all. But when I got my first KF 3.1 I had to cut my ADV's from 18mg to 9mg. Note I use a 2.5 ohm coil and sterile cotton wick. I have now dropped my nic down to 6mg. So a better tank (not necessarily subohm) delivers a greater nic hit IME.
On flavor, stay hydrated, and try a strong mint flavor to refresh your taste buds. It has and does work for me. My finding is that a better tank enhances the flavor, for me at least.
ETA I rewick and dry burn my KF's about once a week or after 6-7 tanks.