I now have rudimentary results, as I am only eyeballing the negatives so far.
I exposed FP4 at 80 and TX at 250. I first developed their samples together for 15 minutes at 68 degrees, with 4 gentle agitations every 30 seconds. This looks almost right for Tri-X, although it visually looks more like a grade 2 negative rather than my preferred softer contrast to be printed grade 3.
The FP4 looked rather cooked after that 15 minute bath, so I tried again at 12 minutes. This still looked too heavy, so I then developed a third sample of FP4 for 10 minutes. This looks close, but again it's probably closer to printing on grade 2 paper.
In a loupe, the grain looks more pronounced than the Rodinal test clips. I'm curious to see the printed differences in tonality. Through the loupe, highlight detail looks better distinguished in the Rodinal negatives, but that could be a matter of not yet finessing the developing times. Overall density is matched fairly well, however.
J