I did some tests to answer my own question. When playing a HD-DVD with DD+, setting the HDMI to bitstream will show "PCM" on my Pioneer 74 receiver. Setting to PCM will show "PCM96" on my receiver. Is PCM96 better than just "PCM" ?
Doing the same with a regular DVD with DTS discrete (Gladiator) will show DTS DISCRETE on my receiver regardless of setting HDMI to bitstream or PCM.
Bottom line, it seems that leaving HDMI at PCM causes no harm and maybe produces the best possible sound (if PCM96 really makes any difference).
I was so happy without HDR...