Hi Walker, well, too many to mention all, but :
With quint converter :
Richard Galliano (CBA C sys), Grayson Masefield (PA). Frank Marocco (PA) (I'm not so shure if Frank did play the quint converter but I suppose so because the quint conv. was/is still the most popular free bass system in the US.)
https://en.wikipedia.org/wiki/Frank_Marocco
With chromatic converter :
Tian Jianan (CBA C sys), Peter Soave (CBA C sys), Vincent Peirani (CBA C sys)
https://fr.wikipedia.org/wiki/Vincent_Peirani
Richard Galliano, Tian Jianan and Peter Soave : all 3 started learning accordion on PA and eventually moved to CBA.
With standard bass :
Johnny Meijer (CBA B sys)
https://en.wikipedia.org/wiki/Johnny_Meijer
Nini Flores (CBA C sys)
https://es.wikipedia.org/wiki/Nini_Flores
IMO:
There are 2 keyboard families : Melodic and Harmonic
- Melodic : PA, CBA, Reuther are melodic keyboard (chromatic scale moves up & down smoothly and scale notes are close together),
- Harmonic : Stradella std. bass, and free bass quint converter are harmonic keyboard (harmonic notes like (maj.) third, fourth and quint are always close to any tonic note). The quint converter is an extended Stradella std. bass on 3 (or 4) octaves.
The advantages (+) of the (melodic) chromatic converter (B or C sys) becomes more or less the disadvantges (-) of the (harmonic) quint converter and inversely.
Chromatic converter (melodic) :
+ Tessitura up to 5 octaves
+ Same fingering as CBA right hand keyboard (if mirror layout)
+ Easy to finger (chromatic) scales, chords and arpegios (if CBA mirror layout & previous experience on CBA std. bass)
+ Easy to finger major, minor, 7th and especially diminished chords (if CBA mirror layout & previous experience on CBA std. bass)
- Can not play std. bass chords while converter is activated
- Heavier (because more complicated) left hand box part resulting in more difficult bellows control
- More difficult to finger open chords (notes spread on several octaves apart)
https://en.wikipedia.org/wiki/Close_and_open_harmony
Quint converter (harmonic) :
+ Easy to play std. bass and maj. chords while quint switch is activated (if previous std. bass practice)
+ Lighter (because easyer built) left hand box part resulting in better bellows control
+ Easy to master maj. scales, maj. chords and maj. arpegios (if previous std. bass practice)
+ Easyer to finger maj. open chords (notes spread on up to 3 octaves apart)
https://en.wikipedia.org/wiki/Close_and_open_harmony
- Tessitura limited to 3 (4) octaves
. Octave jump is not linear for all keys (different fingering) along the 3 (4) octave (imposed by standard bass requirement)
- Fingering is different from right hand keyboard (PA or CBA) (if no previous std. bass practice)
- More difficult to finger (chromatic) scales
- More difficult to finger minor chords and much more difficult to finger diminished chords