I applied G1 to my windscreen around 4 months ago and the stuff is amazing!!
There's a small scratch on my windscreen that's always been annoying me so I got some glass polish while I had my DAS-6 out and said I'd tackle it. I completely forgot I applied the G1 a few months back and when I came out to my car the next morning I could see I removed a perfect circle of G1.
Just goes to show how effective this stuff is. I reapplied another 3 coats on the area affected and it's back to normal now so no big deal!