On 13 Aug 2014, at 09:07 Robert Blackstone <blackstone.robert@gmail.com> wrote

Is it possible, in mkiv, to fine-tune the distance between a chapter head and a section head,  between the end of a section and the following section head, and between a section head and the beginning of the text?

A few days ago I posted this question. There were no reactions, but it is not an urgent matter for me anymore since I found an effective work-around. 
(Although I still wonder whether or not this possibility exists in mkiv,)

I admit having been a bit panicky because a tiny difference in layout between my testversions and the final product, with exactly the same setups, led to a result that more or less forced me to reposition and/or redimension most of my 520 carefully positioned floats, a few days before the deadline. 

Anyway, sorry for the noise.

Best regards,
Robert Blackstone