The 0.4Ω GV Boost Coil is best used for Direct-Lung vaping and is suitable for use for higher VG e-liquids such as those with a VG:PG ratio in the region of 70:30.
The 0.6Ω GV Boost Coil is more suited to Mouth-to-Lung vaping and can be used with e-liquids with a VG:PG ratio in the region of 50:50.
Coil life depends on many factors, including how long you puff for and the wattage you use your coil at. Low resistance coils, such as the 0.4 Ω GV Boost coil, are used at higher wattages and do not last as long as higher resistance coils such as the 0.6 Ω GV Boost coil.
You can extend coil life by priming the coil before usage (see product care), by not going above the recommended wattage and by topping up your tank so that the coil never dries out. With care, GV Boost coils can last anything from a few days to a couple of weeks.