If you're selling a variable power device, higher ohm replacement heads are actually a pretty good idea.
Yup, I've been swapping my various tops on my zmax left and right though, got my mini viv with a 2.8 head on it and my regular vivi with a 1.8 and they hit the same with the zmax set on 8.5w so... the smaller resistance one is pulling less battery power. But, I do understand people like higher resistance on some things and I can see the value so I'll probably get a mixed bag of heads on the next order.

uh oh