I just love Rodinal too much to bypass it except for special cases. It just has a mojo (to me anyway) that nothing touches. (I do mostly lith printing so it's a match made in heaven).
In my tests, adjusting temp within reasonable bounds had no effect on grain. Stronger dilutions most definitely bring more grain. 1+25 shows much more grain than 1+50, and yes, that's with time compensated for tonality. And yes, 1+25 gives you deeper lower mids and risks some shadow detail, but can be a cool look. Good for faces, eyebrows and pupils pop, there's more "drama" to my eye. But more grain for sure, and yes, I tested still life setups with matched highlight tonality in the neg, and enlarged small crops with similar exposure times - very controlled, and yep, "that's more grain for sure". Not "seems like more grain".
With Rodinal, my agitation is very gentle - I don't flip the tank, I gently "swish" it like you'd swirl wine in a glass. 30 to start, 5 seconds every 60, last 20, pour for ten. With Acros I get very very minimal grain - I can hardly see it in the focus mag - but I get the legendary accutance. My times are tested to work with my agitation style. 6x7 Rodinal negs on a lightbox still make me gasp a bit, it's like Imax or something.