As to developer incorporated papers. My experiences have left me to conclude that Forte Polygrade and Polywarmtone are not DI. They are both very responsive to different types of developer and also respond to two bath development.
Apparently Ilford MG Cooltone is developer incorporated. I'm not 100% sure about Ilford MG IV or Warmtone.
These are the only papers I have used for quite some time but have recently acquired some Kentmere Art Classic and Document Art (both FB) and look forward to see how they perform