Diki there are at least two issues I have come across connecting my arrangers to each other, and to an external tone module:
1) What the arranger logic does when you play an accurate chord slightly behind the beat
2) Chord issues caused when you accidentally play the wrong notes, or due to "lag" interpreting the notes you play

I can only speak to issue #2:
I play using the "single finger chord" mode. To play a minor chord, you have to press the root and a black key to its left. For example, G minor = G + F sharp. Sometimes in the heat of battle I might press the F# 0.02 seconds before the G. So Yammy will actually sound the F# major chord (F# A# C#) for 0.02 seconds. When it "registers" my G note, it will release F# and C#, and sound G and D. (Since A# was IS part of the G-minor chord, that note is played for the full duration.) To mask what is happening, Yamaha XF / XG employs portamento control #84. You can even hear this if you listen carefully. It is very noticeable with bright instruments, or those rich in harmonics. There will be extra notes (and depending upon the record tempo, even incorrect chord notation) in the score. If you are sending the output to another device such as a vocaliser, it MAY latch onto the initial, incorrect F# chord which will sound bad.

This is true of the Yamaha PSR-3K and most other Yamahas I have tested, including Tyros and the brand new PSR-S700. But don't take my word for it. It is easy to do a quick record, look at the score, and see for yourself!

Now the Korg PA50 has different logic. It also has a single-finger mode. However when any key is pressed in the chord section, it WAITS about 0.03 seconds to see if you are going to press any more keys before resolving and sounding the chord. So in my example above, if I wanted G-minor, but accidentally pressed the F# first, it will NOT sound an F# major chord. As long as I press the G to the right within 0.03 seconds, it will play the intended G-minor chord without sprinkling two extra grace notes in the score. I prefer this logic approach. The only downside is that it doesn't seem as responsive to fast chord changes because of the slight lag. But as a player, I can anticipate the lag by pressing the chord just before the beat. I can't hide the ugly pitch glide Yammy gives you, which makes certain voices unusable for the left hand.

The times I quoted above are fairly exact. They can be verified by looking at the clocks/beats in the sequencer of a quick record. Not sure if this is the information you needed, but that's my experience with these boards. -Ted