You should try "Pianist 1" rather than "Intelligent." As long as you're already playing chords of 3 notes or more, it shouldn't require you to re-learn any fingering.

The way Korg avoids unwanted notes, is that they have a built-in DELAY for chord acknowledgement. From when you press the first note, I think it opens a "window" of about 20ms duration. It's the notes that are pressed at the END of this period which are used to compute the chord.

Ketron introduced a user-adjustable chord recognition delay on their latest model, the Event, and I've seen this feature in some software arrangers as well although I haven't tested these.

In the special "free play" styles I created for Roland, I did something to achieve a similar result. I have the notes beginning 2 or 3 "ticks" after the start of the style track. At 60 bpm, 3 ticks is 1/40 of a second, or 25ms. So you have that long to get all of your notes down before you'll hear anything. The downside is that you have to "lead" the beat with your chord input, and the arranger feels less responsive (this is somewhat true of Korg also.) The benefit is that it avoids smeary-sounding portamento. I'm not sure how well my approach prevents unwanted notes in the score. Once I switched to looking at live output in the MIDIculous app, I haven't been reviewing recorded scores as much. Hope you find this helpful!