my opinion is that is just is not essential to use an acutance developer to get great results. by far the best solution all round is to use an allrounder developer to keep things in the middle......and you were already doing that!
Pyrocat HD is a great dev and I use it lots. BUT it is more hassle than ready made single solution devs and you do not need to use such things to produce outstanding results.
I use Delta 400 exclusively for my 400 speed shooting, though I usually work in medium format rather than 35mm. However, I have used it for 35 occasionally, and the following developer formula has always given me very good sharpness and fine grain. I rate the film at 200 rather than 400.
Originally Posted by geraldatwork
Try the following for very fine grain and very high sharpness and long tonal scale:
1 liter water
1/2 teaspoon Ascorbic Acid (Vitamin C powder or crystals)
1 teaspoon Sodium Metaborate (Kodalk Balanced Alkali)
4ml 1% Phenidone stock (diluted in 90% isopropyl alcohol)
Delta 400--6 minutes at 70 degrees
Delta 100--9 minutes at 70
FP4+--8 minutes at 70
ACROS--9 minutes at 70.
Sodium carbonate can be substituted for the metaborate with barely noticeable increase in grain, but with considerably shortened development times due to higher alkalinity.
I mix it fresh each time and use it as a one-shot. The simplicity of three ingredients makes the mixing time hardly any longer than keeping an already mixed stock and diluting it.