With a proven 20amp battery (LGhg2) in a single 18650 regulated mod, I feel safe, but would not go over 60 watts.
Have no experience with the Efest.
If I wanted to vape over the 60watt, I would look into a proven 30amp battery.
These are just my conclusions, based on what I've read on ECF.
I only vape around 40 watts.
Bump....