george garside wrote:on a CBA the normal stepped keyboard enables the thumb to be used on the inner rows without it catching on the other rows so it is usable to the choice of the individual player and depending on the needs of a particular part of a particular tune! For those not using the thumb I would suggest giving it a try here and there to see if it has any advantages for you as an individual. I would however not be dogmatic about it being best /worst or whatever!
On a 3 row british chromatic with the normal flat keyboard it is very rare to see anybody using the thumb because there is a danger of getting a thumfull of notes!. There is of course the other point that since you have 2 notes on every button there is less need to charge around all over the place and 4 digits manage very nicely!
My Morino Artiste XS has is "C-griff flach" meaning flat, not stepped, as used mainly in Switzerland. I have no issue in using the thumb on all rows (without hitting multiple buttons at once). The "flat" keyboard has advantages (like in glissando) and disadvantages (harder to feel what row you ar on).
I use both the flat keyboard and the stepped keyboard (on my other accordions).