I've never owned anything other than 4.5" grinders and wonder if a 7" does better on some tasks. For instance,I will soon be torch cutting a few fish mouths in 2&3/8ths pipe and dressing them with grinder for better fit. Will a 7" outperform 4.5 dressing the torch cuts? Same question when grinding out old welds for disassembling damaged 1/4" angle iron frames?