hello khai,
the main reason why i 'moved' from psr to sxkn (yes, 2600 and 1000) is simply the technicality in MIDI programming. i'm by no means a keyboardist (in fact, i'm an organist, playing real pipe orgel, not "drawbar organ" function in the keyboards .. :-) ...), but an ICT system analyst, in particular interest: MIDI.
i am conducting experiment in MIDI and trying to explore capabilities of technics currently. i think, our research team has done with psr MIDI programming.
btw: by saying "programming", what i mean is a true computer/algorithm-controlled programming (including producing new sounds, etc), not keyboard programming, sequencing, as people usually do.
sorry if this frank answer disappoints you, as a keyboardist.
cheers,
y