It depends on where you are riding and what types of weather you will be encountering. I have a Dakar in Australia with the standard windsheild that has been quite adequate for the weather encountered down under (from +6C in Snowy mountains in the rain to over +45C Melbourne area and Queensland). I have the same bike in Canada and have had to ride in below zero C and snow several times this spring and early summer. It is totally inadequate for that. I did a lot of research and decided on the Parabellum, They specialize in BMWs and I had been very happy with the one I had on my R1100R (they don't handle deer very well, but that's another story). I am very happy with the parabellum protection wise, I encountered snow going thru the Rockies last month and have been thru seveal rainstorms, my only problem is that I have removed the dakar windsheild and a bit too much rain comes thru the cut out for the guages, I need to put a smaller sheild back on similar to that on your GS to minimize or elliminate the problem. The Parabellum doesn't look as nice as the factory Dakar windsheild but when the weather gets bad it looks beautiful to me.