While I have not used a Penclic mouse, I am pretty sure that it is inferior to using a small Wacom Intuos graphic tablet instead of a mouse, like I do.
The tablet is no larger than a traditional mouse pad, it is even somewhat smaller.
The stylus, i.e. the pen, is much lighter than any pen-like mouse can be, and it has better resolution and accuracy. Because the pen works contactless and it is very light, you can move it very fast. You can point to any location on the screen faster than with anything else.
Because the pen is so light, I usually retain it between my fingers while I am touch typing, without noticing that I still keep it, which shortens a lot the transitions between typing and using the graphic pointer. I leave the pen on the tablet only before starting to type a long text.
The tablet is switched to "relative" mode at startup, so it behaves as an ordinary mouse. I use it under Linux, where it has excellent support.
The equivalent of the mouse buttons is configurable. I have chosen to touch the tablet with the pen for left click, and to use the two thumb buttons for right click and for double left click.
After I have begun to use a graphic tablet instead of a mouse, trackball, trackpoint or touchpad a couple of years ago, my only regret is that I have not thought to try this earlier, because at least for me it is much more comfortable than the alternatives, and it is also much more precise, being easy to use for drawings or signatures.