Roger, just to confrim do you use Diafine with Delta 3200?
No. I haven't tried it, but my results with TMZ were inferior to conventional developers. Diafine seems to work best with old school films. I was just using that as an example of a case where, whatever a densitometer said, I got results I liked at higher than box speed without excess contrast and with good shadow detail (with Tri-X.) I also use it with Pan F+ 120 because I get a slight usable speed boost - I shoot it at 64 but then many people consider it a 32 film - and it helps to tame the contrast of that film.
For Delta 3200 I get great results with, oddly enough, T-Max developer. I kept it on hand for TMZ in 35mm. When I got medium format cameras I bought some Delta 3200 and naturally tried that and found it works beautifully. For best results with both TMZ and D3200 I develop per instructions for one stop more. So when I shoot at 3200 I develop for the times listed for 6400.