I thought I might try windshield down as I've read or heard somewhere that it may decrease interior dust when running naked. Quite often the dust on my local trails is overwhelming. However if visibility is significantly compromised I'll just ride with it up.
What's compromised are your edge or views along the side of your Jeep. If you think about it, your hood tapers toward the front and then your fenders are lower than it. That helps you to see things on the side. Unlike the old TJ, YJ or CJ before which all had shorter and flat windshields, the JL windshield is slightly curved and it actually taller being that it's slopped more. In other words, with the windshield down, it sits further out and the top corners sit high up and block your edge/side views.
As far as dust goes, there is some truth to what you've read. The windshield creates eddies behind it and that'll encourage dust toward you and onto your dash. However, I hardly think it being down makes enough of a difference if at all especially when you're following a group.