For the AVR, if your dealer likes Denon then it would be good to stay where they’re comfortable. I don’t sell Denon (I lean to Sony for AVRs), but for what you describe I would look at the X1600H (or perhaps the X2600H for the better video processing/options.)
I’m just thinking that you don’t need any more channels/zones; you don’t need the extra HDMI output; and you don’t need lots of power, etc, for a room with lousy acoustics. So, why trade up from there? Maybe ask your dealer what you’d be missing with that model.