Stephen,
I tried Diafine after reading your posts both here & your blogs on FR. I must say I'm rather disappointed. In my testing of Diafine with Tri-X (rated anywhere from 800 to 6400) all I got were "grey" negatives, reminiscent of Rodinal.
That's what I hate about "compensating" developers. It's all mid-tones, barely any highlights at all.
X-Tol on the other hand.... OMG there's a marriage made in heaven!
Just my observation. Love your stuff though. You rock!