I just installed the national cycle plexistar 2 windshield. I like it a lot but a lot of wind still hits my helmet. I'm almost 6ft . I Might just clip on a top piece.
it depends on what you want. I have the Road Comet II fairing. It reduces the wind on my torso at highway speeds but my head/helmet is still in the air. And my arms. It doesn't create extra buffeting. That's how I like it. I don't like looking through a windshield. It definitely doesn't provide much protection in rain.
There are a lot of threads here on windshields--different sizes and experiences. Do a title search and you'll find more than enough information to help make your decision that much harder