Stone: apples and oranges.

DDX, TMax RS are fine grain PQ general purpose developers. They are designed to give full emulsion speed, good sharpness and grain. TMax RS was originally developed to get the most out of TMax films (which are finer grained than more traditional films). Later XTOL became another option which still gives good speed but with finer grain. Ilford presumably developed DDX primarily for its tabular Delta films since it is recommended by Ilford for those films. Compared with say D76/ID11, DDX and TMax RS developers will tend to give slightly higher grain and slightly higher speed.

Perceptol is an extra-fine grain developer. It is a D23-variant designed for finer grain (Metol/Sulfite/Sodium Chloride) via lower pH and a high degree of solvent action. In exhange you get reduced sharpness and a speed loss of at least one stop. You can dilute it for slightly more grain and better sharpness but in my testing even at a 1+3 dilution it is best to accept at least 1 stop of lost speed or else you lose the extra fine grain effect and gain virtually nothing else.

Most people tend to favour sharper developers with more speed than Perceptol with tabular films since they are already relatively fine grained to begin with. I would say Perceptol with a fast tabular film like Delta 3200 is an odd match. It's not as though a super fine grain developer is going to make D3200 look fine grained. You'll just get mushier-looking grain. There's only so much you can do to alter a film's inherent image characteristics - and if you do you inevitably make compromises.

Michael