Have tried the rendering plugin some more and really like the way it looks/feels/behaves. Maybe especially that the interface is clean and easy, but with a button for the advanced settings.
..document on the setting of the SunFlow rendering engine is a bit dated and that an update would be necessary...
Actually, there may be nothing wrong with the document. I suspect that in my case I may be the shortcoming as I am not patient enough to find out more about the terminology 
Thanks again for nice work.
ok
