This is a stock 266 deflector next to a modified 266 deflector. Depending on the saw, and if appearance is a factor, I usually mod them to look like this
Buy the high flow screen. The screen is more of a protector for stuff going into the muffler. I wasn't a fan of screens either. Until it was explained to me how stuff can fly in there.
Yea I have more taken to that recently...especially when I read about someone talking about how their son might fill up daddies saw with pea gravel for him. And seeing as i will have a helper in a few years i may want to reconsider like you say. Also i think of dirt daubers...they plug up all kinds of tiny holes and o always think what about them finding my mufflers I have really thought about it here recently and may put some on the saws with the larger outlets. And then there is like you say the sucking in...but that wont stop sand being sucked in or dust but will stop the other stuff i listed.