Does the 4000 lack a subwoofer, or does it take an external sub?
How does it sound in your space...musically and in terms of surround effects?
I'm always afraid to buy a demo or used, thinking that some novice might crank up the volume and fry something. What kind of price did you get on it? (I don't know if this question violates the no price talk rules of the forum, as your unit is not competing against others in the marketplace).
Are you dissatisfied because the unit is too large, or because it doesn't work well in the acoustics of your room? I understand that you need reflecting walls all around for these units to shine. My living room, unfortunately, has a very large arch behind where I would be sitting, which eliminates a crucial rear surface for surround.
Have you compared the weight and size of your unit with the forthcoming models?
Happy New Year!