New receiver (Onkyo vs Denon vs Denon)

[Ferris]

I will try my best to describe the situation to you, in order to get any advice I can from the experts here.

My setup:
Sony 60GB PS3
Verizon FiOS HD cable
Sony Bravia 40" V-Series HDTV

My dilemma
I will eventually buy a stand-alone BD player. I will be purchasing a sub, a center, 2 fronts, and 2 surround speakers at the outset (the last pair of surrounds will come later). I've found a Denon avr-789 for $450, a Denon avr-889 for $600, and and Onkyo 706 for $600...

My questions to you all are:

Is the Denon 889 better than Onkyo 706? If so, what would I gain by getting the Denon 889 over the Denon 789 aside from an additional HDMI input?

Thanks all!