I asked this same question in the AE forum and was told to render into Animation codec from AE, bring that into FCP and rerender into DVCProHD.
My workflow for this so far, and I have been too busy to investigate any other options, is to render to 8-bit uncompressed from AE and import that into FCP (“stretching” the video from a 1280×720 square comp to a rendered 960×720 file on export). I bring that in to FCP and render to DVCProHD and edit away. No color shift. Then, when I’m going to export from FCP, I dupe my sequence, and change the new seq settings to 8-bit and render any DVCProHD footage to 8-bit uncompressed, then export.
I’ll repost if I find a more straightforward solution. I should also add I am not using the latest drivers or Quicktime and I’m on 10.3.9. I will be updating my system soon however.