As to film grain adding to the perception of sharpness... seems to me I recall some preferred using D-76 straight, undiluted, for that reason. I think they called it "acutance", if I recall correctly. ...
Real men used Rodinal 1:100!
(Actually, the more dilute the developer was, the greater edge effect and chemical sharpening of the image. My old standard film soup was Microdol-X 1:3 with 3 minute agitation cycles. With Tech Pan I mostly used the Kodak liquid Techidol developer, but initially, before they made the right stuff, I mixed my own POTA. Then again there were to two-solution approaches; it was endless ...)
Paul