What would be the harm in using the Kanger 1.2 ohm OCC coil on the Subtank mini below the recommended minimum 12 watts, say 8-10 watts? I'm using an istick 20 btw
Hey mate, as stated there won't be any harm. If you're getting vapor production that you like at those wattages, you're fine.
The issue, mostly with the 0.5ohm coil, is that they use wraps of kanthal and there's a balancing act that goes on in terms of surface area and ohms. If you're using a nice thick gauge of kanthal it takes a bit of wattage to get it heated up, so they usually say 15w because they know that'll get the coil going in a reasonable amount of time.