Its in video 3 posted above. Around 0:40 he starts to play back the recorded piece. Then around 0:55 we start to hear that very apparent change in sound of that instrument. May be that was at the extreme range of pitch shift this can handle.. didn`t sound much though.
I do not think it would be too much of a problem if its done within a reasonable limit and mainly, the styles with accompaniments having longer hold time(like woodwinds, strings etc.) will make it more apparent.
But one thing is for sure, Yamaha surely have nailed the drums and distortion effects. I am happy that inspite of the Audio drums, distortion effects and live feel, they still have a well equalized accompaniment arrangement out of the box. Each to his own though