The last 6 years before I retired I did not pay that portion of my dues. It wasn't that I had to pay and then they didn't use it for political purposes. I never paid it to begin with.
Had I been aware that I could do that, I would have done it sooner.
There was no repurcussions either. You are right on one point, most members aren't even aware that they can opt out. I did my part in informing them when I became aware and was responsible for quite a few members doing it too.
Good for you...too many people don't know their legal options and the unions damn sure don't tell them.