I have only had my SATV flip up for a few months and can't tell you how well it resists scratching, I can say that it is well engineered and the size of the 2 panels are about as close to perfect as you can get, the lower section is low enough that even if it got scratched to hell or full of mud it wouldn't matter much because for the average size person you are looking over it and not through it, being so low it does almost nothing to deflect the air up and over your head when the windshield is open, so you get hit with insects, dirt, etc, but you also get that blast of air on those hot days as if it weren't there. When the windshield is in the open position the pivot point on the upper panel is high enough that it and the struts are above my line of sight and I am 6' tall, when the window is open it is almost as if it weren't there which is what I love about this windshield, mine lives in the up position most of the time, I close it for rain or those times when a lot of crap is being tossed up in front of me. If you felt the need to remove it for races, or a particular trail that you knew had a lot of low branches I would suggest leaving the lower section and only remove the upper panel, it attaches to the frame with 2 bolts on each side and it would probably take all of 5 minutes to remove it, if you want I can get pictures of the mounting hardware tomorrow. In the partially open position, it allows some air in, I am guessing as much or more than a full vented windshield, I hate looking through a windshield and want the option to open it immediately when I want to and close it just as fast when I need to. SATV does offer a 10% discount and free shipping.
I also installed a Pacific Eagle soft rear window with the optional roll-up feature, the clear panel is almost full width and height and has a heavy duty zipper on each side and velcro across the bottom, this allows the vinyl window to be rolled and held by straps at the top, this also allows you to trailer your machine without removing the whole thing, again I hate windows and when it is in the rolled up position it is almost non existent, but there if you need it. This is another well made product, they have added a flap that attaches to the top of the rear cabin wall with velcro so that no dust can pass under the window into the cab, the whole unit is attached to the cage with velcro, fits tight and precise, and can be easily removed if needed. I can also post a few pictures of it tomorrow if you want.
I personally like the wide open feeling, unobstructed vision, and the air flowing through the cab when you don't have windows and when I flip up the front and roll up the back that is exactly what I get.
Something else I noticed is that the noise level increases a bit when I close the front windshield and I would think that the hard rear windshield would have the same effect, I am sure someone on here with 2 fixed panels can give you a better idea about that and tell you about all of the pluses they offer.