20+ years ago when I was welding a lot, the discussion on the cheap vs expensive auto darkening helmets was about the response rate. IIRC the better units went dark in 1/20,000th of a second, the cheaper HF units were more like 1/5,000th of a second. The slower response time allowed more miniscule flash burn that could damage the retinas over time. I haven’t really followed this for most of the last 20 years, but when I bought a big package of welding stuff from a guy a couple years ago it came with four different auto darkening helmets. Those four are decent brands (3M, Optrel, Miller). The optrel is unfortunately not working because it needs a battery, I’m going to send it in at some point. I recently purchased a used tig setup that included a couple of HF and Vulcan helmets. I haven’t decided what I’ll keep vs selling off yet.
I’ve always been concerned about the respiratory side of welding as much as my eyes. I can see myself investing in a PAPR or some sore of supplied air setup. Filtering the air of weld smoke to HEPA standards in my enclosed shop would be nice, but does’t seem feasible like it can be with wood.