Just did my first Acros 100 4X5 last night. If it were any sharper, I'd cut myself handling the prints. I used my own stock soup of phenidone and ascorbic acid dissolved in propylene glycol diluted 1+50 with water and added 1.5 parts of triethanolamine (TEA) for activator. Developed for 8 minutes at 68F.
The recipe has appeared several times, but just in case:
100 ml propylene glycol
10 grams ascorbic or isoascorbic acid
0.25 grams phenidone
heat to about 150F to dissolve.
Both Propylene glycol and TEA are obtainable at www.chenistrystore.com.