Three words: WASTE OF MONEY!
I've tried this stuff out a few times now to stop my dark visor fogging up and no matter how carefully I apply it to the inside of my visor, I end up with blurring / streak marks that are just as distracting as having a misted-up visor!
The past couple of mornings riding into work I've gained a lot of insight into what it must be like to have failing eyesight. One morning the blurring was so bad there is no way I could have read a numberplate at the required legal distance.
I will be buying & fitting a pinlock insert like the one I have on my clear visor, and in the meantime this stuff is going in the bin!