Haven't really seen the cursor shakiness you describe at all. I've got my tablet mapped to span both displays (a 1080p led, and a 20" crt @ 1400x1050), and it acts like a super fast and very precise mouse. I seem to not use it very often at all these days though. My stylus has a busted switch (or more accurately a lost switch after I dropped it on the kitchen tile floor and it skittered off to parts unknown) for doing fancy keyboard combo stuffs. It still works fine as a *mouse replacement* though but I find it easier to mouse with my right hand and type with my left, so less disruptive that way.
So if you map the tablet to the screen, does a tap/contact with the stylus move the pointer to that spot, then a mouse click would be a button on the stylus?
Think you kind of hover with teh stylus to move the mouse, contact is equivalent to left click. So contact + movement = left click plus movement (ie drag, paint, eraser etc.)
What Kos said, I was getting the wrong end of the stick there.
But you can take the stylus away from the tablet and put it down at another spot and the cursor will appear at that point on your screen, you can also hover and move it too. The distance it's effective over is around 0.5cm.
Been scouring ebay, but the medium ones seem rare second hand and expensive new. Don't want a small one again is it just didn't satisfy my needs last time.
Having worked with both, gotta say I prefer the small one as it's more portable and just seems faster as a mouse replacement (you can literally take the cursor across two spanned displays with the flick of a wrist).
OTOH the medium is probably better for /drawing/ (which I don't use it for).