I would like to address 2 points from first-hand, personal experience.
First, having OC'd a fair bit in 3 different states, the public response was almost entirely positive. As someone pointed out, there are probably those who disapprove, but don't say anything. I'm Ok with that; the passive anti's realize that they can't have everything their way, and probably don't even vote. From the perspective of impending legislation, I'm not afraid of them.
Second, I'm curious what exactly Rob means by "activism". I could go either way on that one, depending on the exact definition. Picking fights with cops seems like an all around bad idea to me. Organized, peaceful, political protests seem like a good idea to me. But my take on the term is neither of those. Again, my decision to OC derived directly from my personal experiences, as follows: I had a great childhood, but neither guns nor politics featured greatly in my family. Throughout my adult years, I was pretty much oblivious to firearms in general. I remember hearing about CCW laws in the news once or twice, but I was still quite surprised when I learned that my nephew, a big-city leo, carried off-duty. When I decided to buy my first gun, it was a spur-of-the-moment decision, just because I wanted a new toy. At that time I had no intention of carrying either concealed or open. However, I was aware that there were some laws on the subject, and that guns are intrinsically dangerous, so I proceeded to educate myself in all aspects of my new hobby. Six months later I suddenly looked around and noticed that I had become passionate about self-defense and gun rights. Therefore, my approach to OC as "activism" is to educate the public who are pro-gun but don't know it yet, to inform them that they are allowed to carry and that they will be in good company when they do.