That’s a completely wrong description in the manuals of both keyboards!

In fact, once the pedal is down, it will totally ignore anything you play until you simultaneously play five notes….

Which is EXACTLY what you want to happen! The whole point is to be able to play fairly freely without the chord changing. In normal piano technique, you would tend to lift the sustain just before a change in chords (you rarely want two to sound at the same time) and that is when it reverts to the ‘3 notes’ system, to rapidly pick up on the new chord.

If it only took one note to change a chord while the sustain was down, the chord recognition would totally freak on the slightest run…

I guess it’s one of those ‘lost in translation’ moments!

There are some VERY cool things you can do with this mode, for instance play an open fifth then sustain, the backing will hold that open fifth (no third) and while the sustain is down you can play all kinds of stuff with up to four notes while the backing holds that ostinato. You can play a root chord, pedal, then play around on the five chord to get a revoiced maj7/9 chord, you can play totally dissonantly or go off wherever you want only taking care to not simultaneously press five notes. That’s a heck of a sight easier to achieve without too much thought than having to stick to only two notes, which is all the window the old mode gave you.

Pianists, if you haven’t played an arranger with this mode on it, I really encourage you to try it out. It is a game changer!