It's difficult for me to follow your logic. What is it about Xtol, DD-X, and Ilfosol-3 that you dislike? What exactly happens when you use them together that you disapprove of, and why is it that Delta 400 needs those developers?
And what has happened to Delta 400 that makes it so grainy in D76?
Can you be a little bit more specific?
I agree Delta 400 is fairly grainy. I've used it with Rodinal in medium format, and the perceived sharpness is amazing. I like it for what it is, and could definitely live with it as my only film if it wasn't for me being so tuned to other films.