Upgrade from Onkyo 805 to 875, or ... 605?

[JaysDomain]

I currently have an Onkyo 805 which has been great, except for a few issues (minor rare audio sync lag, 4 sec audio delay); overall I am very happy with it.
I have the opportunity to get back 100% what I paid for the 805 ($700) if I want to, so...

I was wondering if I upgrade to the 875 ($1000 or $300 more) for the Reon chip, will I really notice a difference in DirecTV PQ for SD or HD sources (HDMI), and component sources (Wii & xbox 360); is it worth it to upgrade, and can the Reon upscale be disabled for HDMI/1080p sources?

On the other hand I was thinking maybe I should just downgrade to the 605 for ($400 or $300 less/back) and use it until the new 2008 receivers come out and the audio delay/lag issues are fixed (and the menus are better). What will I be missing in doing this? 5.1 -> 7.1 audio conversion? (I only use 2 HDMI in until next year anyway; PS3 and DirecTV HR20)

I have a Samsung 5084 1080p plasma (1 HDMI from the receiver); PQ is currently excellent for Blu-ray & most unconverted DVD's, excellent to pretty good for most DirecTV HD, and good to ok for DirecTV SD (some content better than others).

I appreciate any thoughts on the subject.