my personal results don't bear this out. I've gone through 4 windshields on my 1992 9000CDT during 250k miles, my wifes 1987 900S with 345k miles has done at least six. Rocks, stones, and sand pitting have had their way with me. It's true that you can get an aftermarket or SAAB OEM replacement windscreen. I've had both and they seem abount equal.
of course, YMMV