I believe that the chainsaw wire mesh is stronger, or at least my Stihl face shield seems tougher than my lexan clear face shield, but anything is better than nothing. I do the same when using a string trimmer. I also wear dust protection. I have had enough days coughing up alfalfa dust from when I used to grow alfalfa (hamster pellets, long story). I take the view that your lungs don’t need all that junk in them.
With the mower deck on the ground, you are out of the direct flight path, but the ricochet debris is a different story.
That said, I have had gravel and small twig sized bits of wood ping off my face shield, but nothing larger, yet.
I’ve said it before, but the great thing about the PT brush mower is that you get to level the brush before you go through it. I once was almost brushed out of my seat and into the path of a brush mower on a standard tractor. Let’s just say that those moments of terror have stayed with me over the years.
My blades haven’t gone very far, at least so far. I have lost a few bolts or bushings over the years, but none since I took to greasing everything before I start mowing for the day. I lift the deck up and put it on metal saw horses, get under it to use an impact wrench to get the bolts and blades off, grease them, and put them back on. It takes ten minutes or so start to finish.
All the best,
Peter