My observations are that with Kodak RA-RT replenisher, Kodak Endura paper is slightly flat and Fuji CA II is too contrasty and often a bit harsh with skin tones.

One way to control contrast that works for me and solves these problems is to use home-brew RA-4 chemistry and adjust the level of carbonate to raise or lower contrast. I have also increased contrast with Kodak RA-RT replenisher by adding carbonate and re-adjusting pH. As for lowering contrast with Kodak developer you can add sulfite but for me using home-brew and using less carbonate works better.