Actually, the Pioneer does in fact support Dolby TrueHD, Plus, and DTS-HD master audio. You can check out their website at
http://www.pioneerelectronics.com/pna/v3/pg/kuro/product/details/0,,2076_310069789_463566618_tab=B,00.html?compName=PNA_V3_ProductDetailsComponent
It also supports HDMI v 1.3a just like the Onkyo. However, the Onkyo does have 3 HDMI inputs to the Pioneer's 2 and I have to agree with Seth=L on the weight issue. I have a Pioneer Elite 56TXi that weighs 48 lbs, this newer, better 91TXh weighs 34lbs and the Onkyo 805 weighs almost 51lbs! Heck, the Onkyo even has that one indicator aof a truly powerful piece of equipment, a detachable power cord. Something Pioneer has left off it's models since the 50 series of Elites.
Also, the fact that the 805 passed THX
Ultra2 certification vs the THX
Select2 the 91TXh has is further proof that it's a more robust machine. I know many don't put much stock in THX certification vs. units that aren't THX certified, but if one passes THX's higher level of testing, then it is definately a more powerful machine! Check out THX's website for the difference in the 2 certs. Ultra2 is suppossed to be able to fill a much larger room with sound than Select2, thus they have more robust amplifier sections.
Oh, one nice thing I noticed abou the 805 when I was at a local electronics store this evening was the blue glow around the volume knob. When you hit the dimmer the first time, it turns off that blue ring around the volume knob without dimming anything else. Subsequent presses of the dimmer button proceed to dime the display until it's completely blank. So no worries about having to live with that bright blue ring around the volume knob when you're in you're dark living room trying to watch a movie.