I originally bought these speakers while on a very tight budget. I had looked at all kinds of options including some of the smaller B&W's (300 series I think), RA Labs, Paradigms (Titans), and a few others. I had heard good things about the AC-650, so I gave them a listen. I liked them quite a bit, but wanted a few extra Hz in the bass. The AC-800 gave me that while preserving the better aspects of the 650. I put them on 24" stands, which might seem awfully tall for a speaker already 19" high, but this raised the tweeters to exactly my ear level and improved the sound tremendously. The simple design of the speakers lends itself well to small tweaks. One of the best was to place a small ring of foam around the tweeter to reduce dispersion. I did not bother with the commercially available rings ($20), but made my own for free. Overall the sound was quite good. I found them to image reasonably well and to project a decent soundstage. They could could play to fairly high levels, but would tend to sound more and more congested as the volume went up. Granted I was using them in a series of large rooms, and given the area they had to fill, they did a pretty good job. They do benefit from being placed two feet or so out into the room which opens up the sound a lot. Stands are a must. Bass, though not earth shaking was good, the "diaduct" port adding quite a bit here. I did find them to be just a bit "chesty" on female vocals, but no so much so as to be distracting. Impedence never dips too low so almost any amplifier can drive them well.
Were it not for the need to baby-proof my house (read, get rid of all heavy spiky, tippy things like speaker stands) I could have been happy with these speakers for quite some time. Sonically I would rate them 3.5, but for value-for dollar they get a 5. My final rating then is an approximate midpoint: