IR , I have used them daily for almost 30 years. Price is high, but nothing has held up as well in our fab shop. Be prepaired to use some air and build your forearms. After you have arms like Popeye, it's as comfortable as writing with a pen.
Previously, I didn't need to have this work done all day. I just had maybe the equivalent of grinding welds for a few hours a week. For that, something like a Metabo 7" at 12 lbs was more than fine. (Bosch makes one at about 11 lbs) -- But we need something light(er) and the pneumatic grinders are light and I'd like to see if that doesn't significantly cut down on user fatigue. I had a Sioux grinder that was probably 30 [?]years old. That s--t the bed.