The best developer for 3200 is DDX in my experience, and I shot it at 3200. Not bad for that speed. Quite good, actually. With Diafine, however, you actually lose a stop or so from what I've heard/read.
I checked my Diafine box and it doesn't list Ilford 3200. Let me know how you like it, please. I have four roll of 3200 I haven't used since I ran out of DDX so I'm in the same boat. Excellent developer DDX is but a bit pricey and can be hard to get sometimes. I switched to Diafine and Rodinal from the one shots (well, Rodinal is one shot but you can develop lots of rolls at 1:50). When I use the 3200, it will be Diafine, so I would be interested in your thoughts. There's nothing on Massive Dev Chart for this combo either.
By the way, my personal favorite is Tri-X in Diafine at 1000-1600 for high-speed.
Ah good ole Tri-X... looks great in everything. I think you can actually soup that stuff in pepper pot soup and it would look okay.