I use the Master MX 3s specifically because of the "gestures" button, it was mandatory for me to replace using the trackpad. It's basically a thumb button you can press and combine with a mouse gesture to do the same thing as finger gestures on the trackpad. I mainly use the gestures left/right (to switch between full screen apps/main dektop) and up (mission control) but it's all configurable. It also has an horizontal scroll wheel that's very useful when using Excel or DB viewers.