I use it full strength. It is a very useful developer if you are printing alt process work that requires a large density range negative. Most films developed over about 8 or 9 minutes will hit gamma infinity in this developer, and IME, this is about a CI of 1.1-1.2 for most films. If you are shooting a scene with a low brightness range and want a full scale print, then you can soup your negative in this and get a nice beefy neg. Be warned, though, that if your scene has a brightness range greater than 5 or 6 stops, you may get an unprintable negative.
This is a developer often used for aerial photography, which by its nature is often a low contrast affair due to atmospheric haze.
It is a clean working developer with very low b+f, which is also a benefit for alt-work. | 
Kodak D-19 
Linear Mode
