If you go to the critque gallery and view the "Abandoned House photograph, you will see that that I took that photo with Tri-X. My personal experience with Tri-X is with the 35mm format and I find that I must fill the frame with the subject!----to get a tonally pleasing 8x10 enalrgement. The magnification for that photo is rouighly 7.5 to 8x, and that's about as far as I care to go with that film.
I realize you are shooting 6x6, so just magnify it until it pleases you, and let the viewers decide it they like or not. Istrongly agree the above statement: "one persons's grain is another's graininess"-----