Hi Bludog,
I have almost the same setup: MC21 > Oppo 105 > Receiver (onkyo TX-NR818) > Sony KDL-55W900A, but each one is linked through HDMI and all the decoding work is done at MC21 level for sound (push PCM 5.1 through HDMI) including room management.
As for Video, I use Red October Standard and Oppo is doing its magic in image processing.
I have use this settings since almost 2 years and I am very happy with it, being playing Blu-ray ripped on a NAS as well as a lot of 2.0 or multi channel music without having to change anything at the receiver side (all signal are set to pass-through untouched).
I did try to use DLNA, but I found the HDMI connection to be much more easy to handle. That was quite a long time ago...
I'll give it a try this weekend and let you know my findings if you are interested in.
Kami