I'm no guru. In fact, any advice I give may also be construed as "adding useless info".
that said, let's look at your 14 points. I'd like to start at :
14. previous set up seems irrelevant , as you're posting because you want something else. (sorry you had to work @BB ), and yes, having a want for better sound quality is why many of us are here, but no, if you've only listened to what they sold, set up and auditioned in their store, doesn't really give you much knowledge as to how it would sound in your room. You would be VERY knowledgeable in what sounds better in a Best Buy showroom, though.
13. when you do room treatments, then make adjustments to what you have, based on what changes those treatments make. until then...you're not there yet.
12. look only at the size of the entire open space, not the 'listening area'... the sound waves don't stay in that smaller space. more relevant to lower frequencies,.. you can set 2 speakers up on the 50 yard line of your closest football field, sit in front of them, and get good sound. When you look at the lower frequencies, and being able to pressurize your listening area, room size rules. That's a large room. Are there openings to other rooms? count that too.
11. you dont care... then it doesn't matter.
10. I believe most current AVR's offer this... not sure on this one. I do know the 818 offers the ability to set that sync at a + or a -, which effectively can delay the audio OR advance the audio (delay the video ? ) greater minds can chime in on this one.
9. not a must.... then it's not a deciding factor.
8. like a dimmer for the display? or eliminating wall shaking bass? or a volume knob? ( sorry, couldn't resist). Your other requirements will eliminate lower level AVR's that wouldn't have this ability to lower the bass ( tone controls?)... so that's not a concern. see below...
7. eliminates very low end, or older units... not a huge deal. see below...
6. no video upconversion doesn't eliminate any options. All AVR's are capable of that.
5. related to above... just run video direct, and audio to the AVR. If you bypass it, it can't have a negative effect.
4. what are you trying to 'adjust', if you don't want video up-conversion, bypass the AVR and make video adjustments in your display, be it a TV or a projector... or look at your sources, and make 'tweaks' there. besides, see below...
3. so don't buy anything that doesn't have some sort of room correction. You won't anyway, because you'll be severely limited in your choices by:
2. pre-outs , aren't found in the lower end offerings from any manufacturer. Any AVR that has these will have #'s 3, 4, 7, and 8 covered anyway.
1... see #2 above... satisfy that 'requirement' and this one isn't an issue.
so, what don't you like about the 818? easily covers what you want... and then some. IMO, YMMV