In THEORY it should be irrelevant whether the source does the decoding or the receiver. After all we are talking 1s and 0s here. Its a bit like the big scam about good quality HDMI cables - they are transporting 1s and 0s not analog.
The only plus I can see from getting the receiver to decode it is so that you can see DTS HD lit up on its display. If that does it for you, then go for bitstream.