Im pretty sure this was a big topic back when i was on the VXR owners forum.
I am sure that it stated somewhere that if anything was to happen to the car and this is fitted, it is possible for the insurance to get out of a claim somehow (i know you said you can see it, but if someone saw the opportunity). Cannot remember the in's and outs though as it was a while ago. I suffer the same problem as you, as in getting into my car and it steaming up. I believe that most of the anti-fog products dont work so probably would solve the issue.
Think its one of those things that we just have to live with
