Looking at expired acufine and diafine on ebay. Experience with these developers, used or new? Experimenting with Kodak 25 tech pan.

I used them both when they came out in the early 1960s. No experience with their extended shelf life, but between the two, Diafine would be safer with extended expiration. This is because the developing agent and accelerator are packaged separately to make separate processing solutions for its two-bath process. Both are very high energy developers, and that makes them totally unsuited for processing Kodak Tech Pan, which requires a low energy developer to reduce its inherent high contrast. After some use, I dropped both of them. The fast acting process of Acufine makes it hard to do fine adjustment to contrast. The divided process of Diafine strips you of all contrast control. Both at reasonably sharp, but yield excessive grain. They were made for a time when almost everyone wanted film speed enhancing developers, and these promised faster film speeds, although they delivered only about half what they promised. With the shift of tastes to image quality over film speed, these developers became dinosaurs, although Diafine still has a few fans out there.