As for split toning, I do not have much experience in this area, but I don't think that split toning can be used a reliable source for influencing the shadow detail or over all contrast in a print, atleast not in a way that could be repeatable on a consistant basis.
What I was refering to was not split toning but Split Filter Printing. I have an Aristo VCL 4500 that I mounted on D-2 and time exposures with a Metrolux II timer. I use the blue light for the shadows and the green light for the highlights. Everything I print is controlled like that and is very repeatable. I am just not sure that two bath developing is relavent to VC paper. Graded papers yes, but the caveat is graded paper is getting harder and harder to find and the choices are getting fewer and fewer. I wish it weren't true as I definately loved Agfa Broveria.