I think it would be very unlikely that you would hear a difference.
Optical cannot carry either the decoded or un-decoded Dolby TrueHD signal.
I haven't got a PS3, so could be wrong, but I don't think at present that it can output Dolby TrueHD as bitstream, which would require the Receiver to do the decoding.
They probably will, not that it will make any difference to the sound.
The only difference will be that the Receiver's screen will say Dolby TrueHD rather than PCM