Developers are like our girl friend, wives or other lovers. They are all genetically about 99.999% alike and in appearance and function about 90% alike. But the small differences really count.
Originally Posted by rogueish
There are subtle differences between developers, even within classes. The most significant difference is between pyro staining and non-staining developers, but even within the category of pyro developers people who really understand how these developers work will find subtle, and sometimes not so subtle, differences in results between PMK, Pyrocat-HD, WD2D, Rollo Pyro, ABC Pyro, etc.
At this time I use Pyrocat-HD for about 80% of my film developing. It is close to ideal for me since I formulated and adjusted it specifically for my own needs. However, for specific situations there are some things that Pyrocat-HD does not perform as well as some other developers. For example, when exposing negatives in very low contrast scenes for printing with AZO or one of the alternative processes the very energetic 1:1:1:7 dilution of ABC Pyro will give better contrast with more reasonable development times. Another example would be when exposing negatives in scenes of very high contrast for printing on silver VC papers. In this situation PMK might well give better results.
So while it may well be true that there are no magic bullets in developers it is equally true that people who understand the characteristics of different developers and how these relate to their printing process know the choice of developer can add significant refinements to printing.
However, for beginners my advice would be to stick with one developer until you understand the reasons why another might give better results.