As someone who has owned Pioneer Elite gear in the past, you won't go wrong.
John mentioned Audyssey, which is more common of an auto-EQ type system than what Pioneer has to try to make corrections in your room's flaws (no reasonable room is perfect in acoustics).
Personally I liked what MCACC did for my horribly imperfect room, but even like the Audyssey, it usually is just a starting point in which you will need to make some fine tune adjustments to your liking.
I've heard a number of times when people are troubleshooting their sound and someone will tell them to turn off Audyssey (or MCACC for that matter) and the person gets the results that they were looking for. Why, I don't know, but it has happened.
I would focus on features that you want and need and of course the price point.
You will probably not go wrong with either receiver. Both are made by great companies. I know that you were looking for a definitive "buy this, it will even pop popcorn and serve you a soda while watching a movie, all for $XXX" but it isn't that clear cut unfortunately.
