Your Denon will be just find, assuming you don't have a room bigger than mine, 8,000 cu ft, and listen at insane levels.
The Q's are very forgiving and will work great to the sides of your couch. If possible have them about ear level or higher when seated, this way the back tweeter will bounce off the rear wall and give you that enveloping sound.
You mention a screen, so I can only assume you have a projector. If so, I have my vp150 mounted right below the screen on a shelf bracket. I put some felt pads near the front to help angle it up a bit. Ideally, you want the tweeters on the center at the same height as the left/right speakers tweeters, but this is not always possible.
To answer your question about HG versus regular Boston Cherry, both are great finishes. Diehard HT folks with screen/projector environments don't want any distractions when watching a movie. Why do you think most of us paint our front/side walls a darker flat colors. The projector will reflect light on the walls, ceiling, etc. The last thing you want is your speakers reflecting/glaring light from your projector.
My first 7.1 setup was mansfield beech vinyl, not even HG, and it was distracting to me. I want to be zoned on the movie and see nothing else, but hear the awesome sounds of the Axiom speakers.
So, for me I would not want HG in a darkened HT Screen/Projector environment. Most of my buddies on the AVSforum Projector threads would agree.
