As soon as the budget allows, I'm getting a larger tablet. I use an Intuos 4 small and it simply does not work with the things that I want to do. There is a relationship (that can be changed) between the tablet and the screen. I can set the tablet so it only works for a portion of my screen. That only works for specific jobs. I use a dual monitor setup. Making the tablet active on a portion of one monitor leaves me with a lot of screen inactive.
There are also features on the Medium that are not available for the small. There are more buttons. The buttons have an LCD screen next to each button, so I can tell what functions I've assigned to each button. Right now, I don't use the buttons because I never remember which button is which. I have enough to remember already.
I've been experimenting with different settings for my pen. There are two buttons on the side of the standard pen, and I only regularly use the lower one. I can also set the eraser to perform a specific function when I tap it on the tablet, which I have not done yet. I'm thinking about setting it for a double-click.
The Intuos manual is extremely well written. The folks there know right brained folks and left brained folks and have created a manual that both types would be happy with. There is a lot of detail, explained in plain English. If you don't read the manual, you won't understand the features and won't get the full benefit of the tablet.