look, if you have back problems in your family history, then there is nothing you can do to avoid it (No matter haw you sit). If you dont have back problems in your family, then there shouldnt be any consequence of slouching or not.donjuan
sorry, it didnt come off the right way...I meant you should do what comes naturally, and if you have back problems running in the family (much like susceptibility to kidney stones..), then there isnt much that can be done for you. If you naturally slump a bit at the piano, it cant be too bad, because if you were to try to sit up straight, you wouldnt be comfortable, and your playing would be negatively affected.
Like bet33 was suggesting with the Glenn Gould example, we really dont know anything about the "Proper way" to sit. I tend to believe it will be different for everyone.donjuan