Built in RDS FM/AM Tuner
HDMI v1.2 (High-Definition Multimedia Interface) switching
THX Select 2 Certified
USB Host Function
Dolby Digital THX EX & Pro Logic IIx Decoders built-in
DTS 96/24 & DTS-ES Discrete 6.1, Matrix 6.1, DTS Neo:6 Decoders
Wide Frequency Response for DVD-Audio and SACD
5.1 channel input & 7.1ch Pre- Output
96kHz / 24bit AD converters
192kHz / 24- Bit D/A Converters
Video up conversion to component
On Screen Display
Front AV connection
MCACC Auto Setup
LCD Learning remote
Based on the specs for the Pioneer, I would say the Denon is an upgrade after everything has been said. You will have to compromise on a few things, but as a whole, what is gained outweighs what you lose in my opinion. 90watts vs. 150watts, no onscreen display, no RDS. Those you can live without as the Denon output is quite good, it isn't like you used 150 watts and unlikely you'd use the 90 watts. Onscreen display for volume is no big deal. There is onscreen display for things like AM/FM control & volume. And RDS is cool, but I think it is not that important. I have it in the car and it does nothing to further my enjoyment of the music.
No, the only big loss is the 8 channel preout as the 789 has none. But it does have 8 channel inputs vs. the Pioneers 6 channel inputs. Personally, if I were to purchase seperate amps, I'd want a seperate pre/pro to go with it. Now what you gain is an additional HDMI input (3 vs. 2), 1.3 vs. 1.2 HDMI version, second zone audio capability, video upconversion via HDMI, and most importantly, Audyssey and Dynamic volume control. Not to mention every audio codec available including Dolby True HD and DTS HD Master.
Yes, the AVR-789 is quite the feature packed unit. Excellent build quality. The remote sucks but if you are like me and have a universal Harmony remote, the remote goes in a drawer anyway.
HOWEVER, I must warn that depending where you get the Denon, the FW may be the old version and need to be updated. This can only be done at a Denon authorized service center which may or may not require you to send the unit in or best case, you have one local and can drop it off. Do get the update before you disconnect the Pioneer so you have something for the week or so the Denon is being updated. Myself, I already sold my Onkyo so I am waiting for after the super bowl to send mine back in to have the update done. I am glad the Denon came with a 2 year warranty (new units only) so no charge for the update. But I have to pay to ship the 789 in and Denon pays to ship back.
I honestly feel the Denon is a worthwhile purchase and don't regret my decision to buy Denon over Onkyo this time around. It is a sexy looking piece of electronics and I have no doubt it will last me for many many years to come.