Where and how you ride is another big consideration...
I've had my full glass windshield for around 1000 miles and have had to stop and clean it twice. Out west, we don't get that much mud and I avoid it if I possibly can. It's all rock, dirt and sand and the dust/dirt just doesn't stick to a glass windshield like it does to plastic. If you get a light film, you can literally blow it off if needed (or go 40+ and it will blow off by itself)
Not many tight woods here either and even if it does get hit and break, it is laminated auto safety class and won't shatter. Just pull the rubber trim and take it out if it breaks and get it replaced at any glass shop.
We ride the dunes going 50+ mph in as low as 25 degree weather and my half poly windshield just didn't cut it when it was that cold. I used to get cold in 30 minutes (even with ski bibs on and 40 degrees) and have to go back to camp to warm up. Now with the full windshield, I can ride for hours and leave the ski bibs in the camper if it is over 35 degrees.