Interesting topic, I was actually in your shoe before. According to the articles I've read, they all claim to set your source (e.g. blue-ray player or TV BOX) to bit-stream if possible. This means it sends the signal to the sound play device (e.g. receiver) to do the audio decoding and then play it to the speakers. If the source is set to PCM, then the source (e.g. blue-ray player) will do the decoding and then the decoded signal gets send to the receiver.
So in short answer, basically choose whether you want the player to do the decoding or the receiver. I suppose everyone will think the receiver should do a better job on audio decoding then the blueray player (including myself) as well as the people who wrote those articles, hence why, bitstream is always recommended. The only reason the articles I've read suggests set the blue-ray player to PCM is when you have an old receiver that cannot decode the audio content to the new format e.g. Dolby TRUE HD or DTS-HS Master, this assumes you have a newer blue-ray player that is capable decoding say Dolby TRUE HD or DTS-HS Master, then let the blue-ray player do the decoding.
HOWEVER, what I have found is very similar to you
@Stealth21, I find PCM sounded louder than bit-stream and it sound more detailed and more open than bit stream...I don't know why... especially the center channel... Some movie I get very low volume on the center channel compare to the front and left channel. But when I set my blue-ray player to PMC, it sound great, the center channel volume is much more in line with the front left and right channel. This is after I have done the room correction calibration on my system.
Another note is if I set my player to bit-stream, my receiver will be "locked" to whatever the movie audio format is recorded e.g. if the movie is Dolby TRUE HD, then my receiver will display Dolby TRUE HD, it is locked, I can't change it. But if I set my player to PCM, I will gain a couple more choice on audio format, not that I am able switch between Dolby TRUE HD and DTS-HS Master, but sometimes my receiver's own own decoding format. I don't know why. So at the end, I decides to trust my ear, so I left it in PCM.
I would be interested to hear from other people if they experienced the same thing or not.