Ron,
I do a bit of work with clocks and the idea of a crossing-out wizard is attractive. I am not sure, however, that scaling the parameters in proportion to the outside diameter alone would meet everybody's needs. The thickness of the rim (outer annulus, or whatever you wish to call it) is often related to the size of the teeth as well as the OD of the wheel. The escape wheel in your picture has quite large teeth in order to do its job while a meshing gear with a high tooth count might be expected to have a narrower rim, not least because the loading would probably be less.
In a similar way, the size of the boss (circle defining the innermost points of the cutouts) would not necessarily increase in diameter in direct proportion to the outside diameter.
This is not intended as a discouraging response, just a contribution to the debate from someone who has so far used CAD only and is intrigued by the thought of a wizard. How hard would it be to design a wizard which allowed the input of the inside diameter of the rim, the outside diameter of the boss, the number of spokes and and the radius of the corner of the cutout next to the boss? Together, of course, with inputs to cover thickness of material, depth of cut etc.
The appearance of clock wheels is quite important and elegance as well as functionality have traditionally been factors influencing quartering.
Hope this is helpful. Peter