Well ... I don't know about the other brands (never used them). It is vastly superior to the OEM window. The water just flies off the thing. If you're going over 35 mph. The down side is, the water loops right over the edge and on to you and everything else. Does it shed water, absolutely. Does it help you stay dry, not even. You'll have just as much water on your face shield with or without the F4.
I'm wondering if they are really as superior to other brands as claimedin regards to shedding water, having great visibilitie during rain, etc. Basically are they as good as the manufacturer says they are.
With that said....I use the Micro-Swirl Edging. This solves the looping over problem. the water just moves over to the sides and top and is channeled down the side ofhte window. This works well.
Then there is the vent. Water pours through this like a running faucet. The only thing I have found that works is, the Handyman's best Friend, duct tape. The coating on the F4 seems to be resistant to the glue on the duct tape. In that the residue left, after pealing the tape off, cleans right off.
It is a thicker window, this got rid of the buffeting I was getting with the OEM window.
This help any?