Many of the HD players and I believe the PS3 is included won't decode lossless DTS. But play it in another manner that is beyond my expertise to describe. Although future updates may fix this.
so I suppose that is one big reason I would run an HDMI cable to the receiver, not necessarily to benefit video, but b/c it will carry all the audio info.
That is correct, unless your receiver has better upscaling such as the Reon video processor that some of the new Onkyo's have it makes more sense as Haoleb stated to go video to video with as few connections as possible. The only reason I run my HDMI through my receiver from my PS3 and Toshiba HD player is for the lossless sound, my DirecTv box goes directly to the TV with HDMI for video and I use a toslink to my receiver for audio.
