Cachet's ab55 is a phenidone version of divided d76. It's panthermic meaning temp has little effect on development. In tanks it's a true compensating developer, giving superior results to diafine and formulary's divided d76. Development can be controlled by making more dilute or less dilute working solutions of the "A" bath. While best results are obtained in tank inversion processing it will indeed work with a jobo. I use mine at the slowest rpm (except when introducing the "b" bath) and yes, I do dilute the "a" solution...anywhere from 1:1 to 1:.5.