diki, i tried to duplicate this, in my E60, both with split and whole mode selected in the main screen.
having the type: piano style and zone: whole, in the arranger setting screen, i start playing.
if the setting was whole in the main screen, yes, i can play piano on whole keyboard, as a pianist would do, having the accomp on also.
anyway, in arranger setting screen, while playing, if i press type: standard button, the accomp stops, only drums remain, the accomp comes back when i press keys, but the
zone:whole does not change, it remains whole, does not go to zone: left, as you said. also, the keyboard
more remains whole.
so, i couldnt go on with the experiment you propose, simply because the first part of it does not duplicate in my keyboard...

is it good? bad?