I find that they lack torque. Also sometimes you hit a softer spot and they kinda try to get away if you're still putting the same force. DeWalt makes a 1/4" die grinder that's cordless and brushless. It's amazing. 20v 2Ah battery lasts forever, no cord to distract you, and the torque is amazing even at like ten rpm. Oh right, variable speed 0-30,000 rpm. I wish they'd made them when I was doing stone for a living. I can't imagine where I'd be. Outside, maybe by the river in the wind, you can carve some large pieces, or even smaller ones go so so fast and you don't need to worry about dusting up your entire life lol..
I'll try for a link
*This price is about what I paid, but it was all one price, nothing about import fees. It was still ~$200 https://www.amazon.ca/DEWALT-DCG426B-Variable-Speed-Grinder/dp/B076S9YBMH
They make a die grinder which is this one.
DEWALT 20V MAX Die Grinder, Variable Speed, 1-1/2-Inch, Tool Only (DCG426B) https://www.amazon.com/dp/B076S9YBMH/ref=cm_sw_r_cp_api_glt_fabc_NG3C5R5HT40J3WWPQD3M
Which I’ve just bought….. couldn’t pass the 40 percent discount….. wasn’t expecting that.
Please someone correct me if I'm wrong but the only cordless die grinder DeWalt makes that I'm aware of is the DCG426B