When comparing electric to pneumatic, you should make sure you are comparing apples to apples. Most electrics are rotary sanders, most pneumatics are ROS. Dennis Weiner's post sums up the available electric ROS with a 3 inch diameter or smaller sanding head. I use electric rotary drills mostly but want to mention that ROS sanders can take advantage of the new mesh sand papers that cut better and last longer. Specifically, the 3M Cubitron II sanding disks win just about every review/evaluation that I have seen on YouTube. My person experience with the Cubitron II is that they work great with ROS but are nothing special in a rotary drill.