I still don't buy the concept that the distance of travel on the tablet must correspond to that seen on screen. Your brain does the translation without any fuss at all. This has been your experience since you first started to scribble as a child, and is the same brain/eye function as is used every moment of your waking life. For example - when I write with my eyes up close to the paper, the pencil and hand fill over 300% more of my visual field than when I write at arm's length. I don't need to make any conscious adaptation however - in both scenarios I know it is my hand writing - it is effectively the same experience, and my brain does all the work behind the scenes so efficiently that I am not even aware of how relatively large or small my hand appears in my visual field. The same principle applies to tablet and screen sizes. If you are comfortable with the physical feel and function of a tablet and pen setup then that's the right setup for you, irrespective of whether you are working with a 13" laptop or cinema display.
Regarding the choice of tablet - I personally go for a small one because it does everything I need it to do; uses up less valuable desk space; is easily movable and is less expensive. If I feel like getting away from my work desk for a while I can use it with my laptop in an easy chair. I have tried larger ones and found them unwieldy, bulky and physically hard work. I am fully aware that a lot of people prefer larger tablets and would probably find a small one restrictive - it's a matter of choice and what feels best.