My personal bias is to use the player as a transport -- i.e., in Source Direct mode. I do any necessary imaging adjustments in my pre-pro.
Used that way, into my Anthem Statement D2v, I find picture quality between the Oppo BDP-83 and the PS3 identical for Blu-Ray (i.e., excellent). SD-DVD playback has gone through some recent changes in the Oppo firmware so I'm going to reserve comment, but the PS3 has severe disadvantages since it is incapable of HDMI 480i output and its de-interlacing is seriously under par. CD playback quality in the Oppo is superior to the PS3 (HDMI audio output for both).