When comparing the types and concentrations of developing agent(s) in developers, it is critical to look at the operating pH (ie alkalinity) of each of the formulas. Different developing agents become active at different pH levels. Metol, for example, can develop film at an essentially neutral pH (~7 - as in the case of D-25) albeit with long development times. Other agents such as Hydroquionone, Catechol and and p-Aminophenol need significantly higher alkalinity to function as primary developing agents. You can't compare the function of Hydroquinone in D-76 to its function in DK-60a which contains a stronger alkali, and much more of it.

Bottom line, you can't compare developers by looking only at the developing agents and their concentrations. The other parts of any scientifically balanced developer formula are just as important, if not more important in determining how the developing agents will work, and in determining the working characteristics of the developer. Therefore it is incorrect to characterize a developer as low or high contrast merely based on whether it contains Metol or Metol and Hydroquionone. D-23 was designed to work very similarly to D-76. That said, there is nothing stopping you from trying dilute D-23. Maybe it will help, maybe it won't. Worth a test.

With respect to Pyro, personally I'd suggest either a specialized low contrast developer, or a compensating developer such as FX-2 before going to Pyro, particularly if you are looking for higher film speed than you are getting from D-76. While certain superadditive formulations such as Pyrocat are said to give full film speed (like D-76), most general purpose Pyro/Catechol staining developers do not, nor are they inherently low contrast developers. There are, however, some highly dilute Catechol developers formulated for very low contrast. Maybe those would be worth a try. If you want to try Pyrocat, what you may want to try is some sort of stand or semi-stand technique. While this can be disastrous with many staining developers, it is said to work with Pyrocat, and may result in decreased contrast with half decent film speed.

In the end, you're using a high contrast film. It isn't easy to tame the contrast without losing film speed. Who knows, maybe your EI 25 is all you're going to get. How do we know all these other people are getting EI 80 and higher? Under what conditions? Do they have good shadow detail? Etc.