Even if there was a measurable difference (probably not), I will subjectively say that 99.99999999999999999999999999999% of the setups out there would not benefit, including my own. However, I don't believe there is any difference at all, just going by subjective experience. I have a double digit ft wide screen in a dedicated dark area, coupled with a high quality projector, and I've ran stuff directly to PJ a couple of times, and of course normally thru the receiver. The source and setup are so overwhelmingly more important it's not even funny.
I've asked silly questions myself, though not related, like if there are any color saturation differences among BDPs. The answer, for all intents and purposes, was no.
Now, if you own an HDMI 1.3 receiver, but upgrade to 3D video, you will likely have to use two outputs anyways (which I believe the Pana player does, so that your receiver is not instantly outdated).