I have no personal experience with the Fortress products.
A couple of members put them on their 800 crew, they said they could feel the added weight of the cab. They stated it felt more top heavy and changed how the Ranger felt while driving. It appears to be a well made product though.
I prefer the Polaris cab accessories over all mfgs that I have seen. The Polaris fit and finish are excellent. The Polaris windshield and back glass are frameless, which allows for a better view. If you purchase the Polaris front windshield fixed (glass), be sure to purchase the wiper ready version.
I personally have the tip out (glass) with wiper/washer setup and would definitely purchase it again.