Ergonomic Mice

I want to know what is comfortable and practical, keyboard and mouse on top of your desk or Keyboard Shelf ergonomic chair. Ergonomic keyboard tray does not seem very popular, but they claim to be more ergonomic. What do you think? These are the advantages and disadvantages of both keyboard and mouse on top of the desk: one benefits, you can lean forward and rest your arms on your desktop (you do not armchair) 2 cheaper 3.You do not pull the keyboard every time you write or use a mouse Cons. Do not give up so much space on your desk for a keyboard tray that both brands write. Maybe less than ergonomic keyboard tray Ergonomic Keyboard Tray with Keyboard and mouse behind your desk to free up space to write the second paragraph. more ergonomic than the top of the desktop at a disadvantage. Dragging the box every time you write or use a mouse. expensive Note: Back to the keyboard tray is designed to provide ergonomic effect by writing that I do not know if it's true or pay the difference.