Karl, I tried those muffs years ago. I found them to be unsafe because I take my hsnds off the grips too often when riding -- especially in the city.
I thought about them the other morning when riding at 40mph in 20° temps. Those conditions strain the ability of my heated gloves.
As for a screen - of any kind - I guess I just prefer to deal with cold wind by using effective clothing ( strange as that seems to some)
It's not a matter of forward vision. ....just prefer to ride as I always have since I was 20.
Screen or no screen, probably not wise to go off into the night at temps much below 30°F. My current gear can handle that.
I can offer no good reason to keep refusing to ride behind a screen!
Maybe when I'm old (er)?
Stig