Have you tried riding with it off?? (although it is kinda cold here in PA these days for that)
I would think it's of some benefit. Even a small shield can help deflect wind and/or bugs.
A lot has to do with how it's positioned. Nearly straight up will do the most deflecting. Leaned way back will deflect less and may even aim some of them bugs more at you instead of away from you.
In PA, especially in the winter months, you would probably be much happier with a bigger windshield, like the National Cycle Plexistar 2 (um, the one I use), or its bigger brother--the Plexifairing 3.
A larger windshield has many advantages: protection from wind (and thus, wind chill factor), protection from wind noise (both reducing rider fatigue), protection from small or large (ouch!!!) insects, protection from the occasional loose piece of gravel that gets thrown at you (mega-ouch!!!), and of course, protection from rain (you'll get caught out in it, sooner or later).
Fortunately, judging from the posts on this website, a number of worthy windshields apparently fit our bike.
You can start a search for one, by visiting National Cycle's website:
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