When I use my laptop at a coffee or during commuting, I use the touchpad. Then I like using a dock (Plank) to launch and switch between applications, lots of big shortcuts the desktop, and big icons for files and folders that are easy to reach with the touchpad. Also I don't like a fixed panel occupying space on the small laptop screen.
However then I spend an afternoon or a weekend working at home, connecting a nice big screen, keyboard and mouse to the laptop. Then I prefer a classical thin panel at the bottom of the big screen, with the Mate main menu and small icons I can very precisely point at with the mouse, and a clean desktop without shortcuts.
While using Ubuntu I had been switching between the 2 modes by having two desktop installed, Mate and Gnome 3, and choosing which one to use at the login screen. Now I have installed Debian with Mate and, before installing Gnome 3, I have the question, ¿Isn't it possible to configure Mate in such way that I can choose between the two configurations I have described without having to install a second desktop or a different user?