I've read most. Such as the ipv series have 95 percent efficiency. I'm sure some will say mech mods are more efficient but oh well. How far off are these cheap Chinese devices? I read the cloupor mini was notorious for being inaccurate. I have sense upgraded to an ipv d2. But ive always heard stuff like the sx mini and the evolv chips are most accurate. Innokin claims the mvp 3.0 is the most accurate. What do you guys think?