It's true that most of us five fingers on each hand. [I use my RH strictly for melody, so in my case it's only the left hand that matters.] Some of us just don't have copious skill or time to practice. The problem is, for people transitioning from Roland, GEM, Casio, or even Ketron since 2015 or so... if those folks were making full use of the ergonomic aids their keyboards have to offer (aka "Chord Intelligence"), they would not be able to play Giglad without re-learning.

Consider: the best typists can accurately type 90-100 words per minute. Meanwhile, stenographers can type 200-250 words per minute using a special ergonomic keyboard. Modern cars with automatic transmissions, dual-clutch, etc., are faster in a straight line, and even around the Nuburgring compared the best human drivers with a stickshift. Technology is a great equalizer and force multiplier. If you're playing a fast progression where the chord and bass note change on multiple successive beats, one finger major chords and two-finger slash chords HAVE to be faster and easier (although Roland doesn't penalize you for playing all of the notes.) Often times being able to trigger the chord with a subset of notes makes the difference between moving your whole hand, or reaching the chord(s) from your current position. And for me personally, hand "jumps" are an almost guaranteed mistake or late note. I've even thought about sticking a post-it flag to the SIDE of a key, as an aid to hand positioning.

As I see it, organists and arranger players are playing three parts simultaneously: melody, harmony and bass. Perhaps I wouldn't mind 3- and 4-finger chords so much if I also had the skill to kick pedals, because then my feet would control the bass and any convenient inversion would do. But I've never tried pedals, so to control both the bass and harmony my left hand ends up jumping around like Daffy Duck on speed. If I'm going to play three parts "live," I want all the help that technology can afford!

My point remains -- there's no logical reason to limit slash chord recognition to 3-finger chords. By making "on bass" a separate setting that can be used with ANY chord recognition mode (as on Roland, Ketron, etc.), it helps folks like me without making anyone worse off. It's just software, easy enough to change it to accommodate players of all backgrounds and skills.