I like the Pinloc also, but they came on my Nolan & Shoei helmets, so I don't have any experience in buying or installing one on an existing shield. I have had trouble getting them adjusted tight against the shield after a while, especially around the bottom center, and I get condensation there.
The main negative about the Pinlocs to me is they cut down light transmission, I believe their literature says about 20%, so you lose just a little clarity of vision. The instructions warn you that they are not for use at night for this reason, but who is going to go to the trouble to remove it at night. I wear glasses, so this adds another layer of plastic to see through, plus one more if you are one of those who look through your windshield instead of over it (I don't). And if you are a senior, like many of us, you are probably starting to get cataracts on your biological lenses. All of that can add up to a noticeable loss of clarity.
Removing it for night riding takes a few minutes, depending on how hard it is to remove the shield from your helmet, and you have to store it somewhere. Which brings up another concern, they scratch easily, so also be careful when cleaning them.
Having said all that, I still like the Pinloc system better than defog products. I'm getting new lenses for my glasses, and will probably have my cataracts removed in the next year, so I'll be good to go then. In the meantime, stay out of my way!:yikes: