Excerpt from Keyboard Magazine, April 2007 issue, "Arrangers un-cheesed", by Stephen Fortner:

"The Pa800 features a new RX grand piano sound (this stands for “Real eXperience” in Korg’s marketing materials), and I hope Korg takes this as a complement: The keyboard action, which is silky smooth, has aftertouch, and seems perfectly matched to every other sound in the machine, doesn’t do this piano justice. With some practice, I got good dynamic and harmonic range from it, but played via MIDI on a weighted controller, it becomes a whole new instrument. By any hardware keyboard standards, arranger or otherwise, this is a world-class sound.

When it comes to following your chord changes in a way that makes musical sense and doesn’t come off as mechanical, all arrangers at this price and above are very good. That said, the Pa800 is my current favorite. One reason is its top-notch chord recognition. Like on all Pa models, a pair of buttons determines whether the keyboard scans the left hand, right hand, or both to tell what chords you intend, which is often a function of some less-obvious mode choice on other arrangers. In practice, the display identified just about every altered chord and extension I threw at it, including augmented, diminished, sixth with and without an added ninth, major seventh (with a major or minor third), flat and sharp ninths, suspended second and fourth, even sharp 11th. With Bass Inversion active (a button found on many arrangers, including the rest of the Pa series, the Ketron SD-5, Generalmusic Genesys Pro S, and Roland E-80), even “slash” chords such as Fmaj7/A were recognized properly. It wasn’t just lip service either: Style playback was uncannily hip to the displayed chord, and seemingly, to my intentions. Was there the occasional clam? Yes, but less frequently than with most hired guns I’ve worked with, and the Pa800 doesn’t ever raid the buffet."

link to article here