I have asked this question before, and recieved the same answers. Most folks say it's no problem and I believe them.
My problem is, I can't bring myself to shoot holes in a perfectly good blind! I know, that's what they are made for maybe I am just too cheap.
Turkeys don't seem to mind the windows being open. I keep the netting up on side windows so I can see out but they can't see in. Like most have said, deer really don't like the "black holes" that uncovered windows cause. Again, I leave as many windows screened in as I can, but zip down the mesh on the windows I plan to shoot through.
For turkeys, I just set the blind up under over hanging branches making sure that I am in the shade. For deer, I spend a lot of time brushing in the blind. I make sure the windows I am gonna leave un-meshed are brushed over (without obstructing my shot). I leave the windows uncovered even when I am not hunting so nothing will look different when I am in the blind.
I have found that a leafy branch 1-2 feet or so in front of the window does just as much good as one right against it and will not block my shot.
I am sure that shooting through the mesh is no problem. If I can put in a little work so I don't have too, that's better for me.
OkKeith