TriX in Pyrocat makes an absolute grainless 8x10 contact print - In 6x6 it makes a grainless 5x7 print. I am usually not in the mood for grain or motion blur - unless the motion is part of the subject so I am not a big fan of enlarging TRI X in roll film formats. HP5 has a kind of mottled paisley shaped grain pattern that makes enalrgements appear less grainy. TriX has its distinctive pinpoint grain that gives it that raxor sharp accutance. In 4x5 format enlarged to a 16x20 I notice a big difference in the grain of FP4 vs TriX. Although TriX is acceptable, the FP4 is noticably smoother. I do like to stop down and TriX will let me do that if there is a breeze. So I keep 2 graphlexes full of TriX and one full of FP4 for 4x5. I think HP5 pushes smoother than TriX. I find that TriX in Microdol for roll film enlarges pretty good. I have to rate it at 200 - but then I rate FP4 at 80 so it is still a pretty good difference. Of course the ultimate enlargable film is Tech Pan - I do use Pan F 50 for Portraits that will get enlarged when I must use MF. There is nothing quite like a LF portrait though and I prefer that if it is possible - it usually is not though. Sorry for the excessive rambling- I have given a lot of thought to exactly this topic. Still debate each time as well.