3 note chords restrict what you can do on the left. (The ultimate freedom coming from even more simplification in the form of single note free bass.)
You can do some great things with polychords on traditional Stradella (eg C triad + G triad = Cmaj9, but some things like maj/min 6th chords arenât possible. Thats a big restriction to the growing number of people studying Barry Harris (recently deceased) whoâs method is based on 6th chords (+ diminished chords).
Most harmony, including sophisticated harmony, is (in our culture) constructed from min and maj thirds. By removing the 5ths (which btw, are largely a hindrance if you want b5 or aug chords) youâre left with a big construction kit of minor and major pairs from which you can build absolutely anything.
You get a less duplicative maj 7 chord with 2 vertically adjacent buttons in the major column. (Meaning less wasted air.)
You get a maj 6th chord with 2 vertically adjacent buttons on the minor column.
You get a min 6th chord using a maj and minor button 6 rows apart. (this seems the most clunky voicing, and I may very well be wrong⊠Iâm just mentally constructing this.
A m7b5 chord is just an inverted m6th chord.
You also get a dom 7th row consisting only of scale step 3 and b7, the 2 most critical leading tones in tonal music.
Combine a dim button and dom 7th button 3 rows apart and you get a full diminished chord, all 4 notes (dim and 7th column are both tritones.)
Iâm also guessing you can construct Barry Harrisâs famous dim6th (bebop) scales and movements fairly easily.
Iâve never actually touched a CJS instrument, and probably never will, since I play CBA/freebass so I get all this stuff pretty much out of the box (as Iâve ranted on about endlessly in other posts.

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But yeah, less really does get you a lot more by simply dropping the 5ths, and saves you a ton of air in the bargain.
- Jerry