Interesting, I just noticed that the issue in 5.5 may be contained to DNXHD 444 I just tested it with DNXHD 36 and it looked fine.
This is what DNXHD 444 looks like in premiere 5.5:
And while playing back:
Obviously though, for workflow, I'm much more concerned about the broken fcpxml workflow. I had hoped that it would be easy enough to get clients to install the DNXHD codec on their machine and I would be able to continue just as I was when delivering prores. Now it seems that may not be the case.