On the 700 I've got a two piece and like it a lot. It's he hard coat version which has been very scratch resistant. I like it so much that I plan on getting it again when I get be P1000.
One thought is, during the summer I will take the lower piece off because it directs wind right in your face. Even in the summer it's annoying to have it hit you in be face. But during the cooler months, I can tilt it out for a little air or remove it or completely shut it.
Also, I tow with it installed at interstate speeds and haven't had issues. Not saying I'd recommend it but I haven't had problems.