I have a Huntsman VXL 4x4 auto darken lens and have used it for about 4 years now. When I was looking it was about the best priced 4x4 lens. It has 4 sensors on it and can darken even if 3 of the 4 are covered, adjustable darkness, sensitivity and delay settings so it makes it really adjustable. I bought a cheap helmet with a solid lens in it then bought the Huntsman auto darken unit and if I remember right I was about in the $100-150 range... I've never had any problems with getting flash burn from the batteries not working, as soon as they start to get low there is a little light that flashes. I dont wait for them to stop working, I just change them as soon as the light first comes on. Come to think of it, I think I've only had to change the batteries maybe twice... I dont use it every day, but I do use it at work and at home so it gets its fair share of time on.
I have however forgot to turn the darkness back up after using the cutting torch, or just forgetting to turn it on and got little spots for a minute, but never flash burn from the batteries not working
There was a new lens I noticed in Prax-Air the last time i was in there that was a 4x4 lens that had a very nice large opening... probably about 3 1/4 x 4 (vs mine which is actually only 2 1/2 x 4) I didn't price it, but i think it would be pretty sweet to have the extra field of view when your welding in crazy positions.
