Wow DF, great stuff. I need to do some testing!
Pardon me if this is simply restating the obvious here or correct me if I haven't got the concept.
Using this method I should be able to (within certain limits);
1 - Place my exposure based on what is best for my subject on any given film.
2 - Decide how much shadow detail I want in relation to my subject and adjust this with development time.
3 - Decide how much highlight detail I want in relation to my subject and adjust this with agitation.
So, for a back-lit afternoon portrait I could;
1 - set the camera by using an incident reading "under their nose" to place the main subject on the film exactly where it needs to be to print nicely,
2 - then extend or reduce development time a bit to control the details in the bushes behind them, and
3 - enhance or reduce my agitation to control the details in the sky.