The KN5000 does NOT have the Dynamic Arranger feature. It was on the 3000, but Technics dropped it. I'm not sure if it is back on the 6000/6500.
My Roland Em2000 has it (as does the G1000). The Korg pa80 does NOT have it.
What it does is to vary the accomp part volumes according to velocity. So, if you hit the left-hand chord hard, all 5 auto accomp parts play at full volume. A softer touch on the left chord might cause accomp1, and accomp2 to mute. On the Roland, you can set up exactly which accomp parts will be affected and what the volume levels should be as a result. It is an incredible feature - but require skill to use & patience to set up.
The pa80 does have what they call Dynamic Arrangement. But all it does is trigger a break, fill or style variation change according to the velocity of your left-hand chords. It is very much more limited than true Dynamic Accompaniment.
Tom