I don't trust ZNA's. There are clones of them everywhere with God knows what kind of chip inside of them. I had one for a few months, and the fire button started dying out almost to the point of auto firing. I have an IPV mini 30w, and even with the problems I've had with it, such as reading ohms too low - which was an issue of wire gauges being too thin and the solder points being weak - it's still a better mod than the ZNA I had.
I'm sure P4Y has corrected these issues with the IPV mini 2, as it has a different chip (the 30w has the sx130 and I believe the 70w has one of the sx330 versions). My Sigelei 50w Vr2 has one of the sx330 version chips inside and I haven't had any problems with it at all.