The TX-SR805 is the better featured receiver, and certainly more powerful. THX Ultra certification helps ensure you have enough power to achieve reference levels in a larger room, so it does mean something. It also has some different post-processing modes that some people like to use. The TX-SR805 does upconvert to 1080p, but only with HDMI devices. It will upconvert the Component to 1080i I believe, but if you use the HDMI output for all input sources (digital and analog) it will only allow up to 720p for the analog sources over HDMI.
You can't use the TrueHD and DTS-HD master audio processing abilities of this receiver yet because no player out now can output bitstream HD audio. You can have the player process it internally and send it out as 8 channel LPCM, which is very good and may not be any different from having the receiver handle the processing. So if you wanted, you could save a little and get the RX-V861 because it will handle the 8 channel LPCM.
I would like to add, and I realize weight doesn't mean everything. But the Onkyo has over 20 pounds on the RX-V861, which is about a few pounds shy of half the weight of the Onkyo.
