Bests & Worsts Reviews from Amazon

This 'Professional' version is just a money-grab. The older models are way better. I've been using the K400 and K400r for years. My issue with the K400r is that it replaces the K400 and makes unnecessary changes like defaulting F keys to Media buttons. You need software to reverse this behavior. The K400 Professional was the answer to this. It had the standard behavior for F keys, and it looks sharper than the other 2 models. That's where the pro's end. The touchpad has terrible sensitivity compared to either the K400 or K400r. The Page Up and Page Down keys are half the size to make room for a larger right Shift key. The most frustrating aspect of this keyboard is the touchpad. The buttons are not as responsive as the older models. A simple drag and drop using the physical button and the touchpad will fail after a few pixels, and the button will start clicking random things as the cursor moves. Furthermore, forget about anything that requires double clicking and dragging anything with the touchpad without using the buttons. It simply doesn't do this. I tested with a few applications and dragging this way does not work. It certainly seems like Logitech decided to release this product in black, replace the F keys to the default behavior, call it Professional version and charge $40, while at the same time completely making it unusable and much inferior to the non-Professional version. Skip this and get a K400r and use the Setpoint software to flip the F buttons behavior.