I've never cut copper (accept tubing) but I do use my rtx quite a bit. I often snap/shatter the regular cutting discs from applying too much force. The reinforced ones are thicker but I haven't broken one yet and they last significantly longer than regular discs. I'm looking to pick up some
diamond discs since I've read about people doing tons of case mods and cutting while barely wearing away a single disc compared to reinforced.