Well, it's fun to see how this thread went on. As some of you know, I was in the same position last summer (you can read it on the 'Diafine' thread), and after somebody here provided a link, found the only (I think) place that will ship it worldwide via normal USPS and not UPS or Fedex, that was Huron Camera. They don't stock it but usually get it 3-4 days after you place the order. Shipping was $12 for 2 gallon cartons, not bad for who-knows-how-many years of developer, it got here in 3 weeks via slow boat (not a bad timing) as this thing can't fly.
I simply LOVE the stuff, and it's true, the B solution gets real ugly, loses that nice creamy color and gets a dull brown, also gathers residues from the developing process, so you end getting a brown bottle with black worms floating around 🙂 (that can be filtered, of course).
The truth is that the stuff simply works GREAT even if it's that ugly, and I can't now think on a reason to go get another developer, maybe for experiments but diafine seems made for lazy people so I'm too lazy for that... 😛
As for agitation, I haven't found significant differences, I move the tank at first to get rid of any possible bubbles and then do a couple or three small inversions during the process. What seems important to me is to have the stop bath (water) and the fixer at the same temp. For that I always have a 5 litre bottle filled with tap water at room temp and use that as a stop and post-fixer bath as well. Then finally I give the usual bath in distilled water with some wetting agent.
I mostly use Neopan 400 rated at 640 (not that important in the end as now I nearly always guess the exposure) and Tri-X at 1250. Both look great. Also had very good results with FP4 rated at 250.
So far, Diafine and me, it's a love story.