Thomas,
I've always used Kodak's selenium toner, but just never stronger than a 10% solution. Are you printing on Ilford's MGIV FB, if so, how much of D-max increase do you perceive with it. Currently, at a 10% strength with MGIV FB, I'm not really having to account for the important shadows in printing, meaning, I can print them the way that I want, and after toning the shadows are strengthened with the detail in those shadows still satisfactory. I was wandering if going stronger on the selenium for more of a color shift, if I would then have to go easier on the shadows in printing and then rely on the Dmax increase in toning to get them where I wanted them to be originally.