I guess what I am not understanding is, why is everyone so interested in the 605s ability to scale? After all, the Genesis chip is not known for its outstanding scaling capability and your display can probably perform equal to it. Onkyo does not even claim it is a feature they support from the 805 down. I would think they would advertise such a feature if it was any good.
If you are looking for "quality" scaling, then look at the 875/905.
The Cave: Sony VPL-VW600ES, 110" Elite Fixed, Oppo BDP-103D, Sony FMP-X10 (Pre-order), Apple TV 3, Yamaha CX-A5000, 7 x Emotiva XPA-1L, Sonus Faber Venere 2.5, Sonus Faber Venere Center, 4 x Emotiva ERD-1, 2 x HSU ULS-15