Bill Tindall
It certainly is an elegant potential solution to the problem of precise shoulders and yours is elegantly executed.

I can think of several "theoretical" reasons it won't continue to deliver precise shoulder lines. If you will humor my skepticism, tell us a year from now how it worked out.

Once scribed, a shoulder line can be whacked approximately with a band saw, or hand saw if you must, and then chiseled to the scribe line in what seems to me to be no more time than this sawing arrangement. For softer woods a single paring cut suffices and these can be made along the base line quickly. I find the scribe and pare to be the only reliably way I can get tight shoulders and many others use it. I never was successful cutting them reliably on a table saw.