perks of a physical grand piano that I haven't seen in any digital piano yet: you can half-release and re-press the sostenuto pedal to sustain additional notes to it without cancelling the existing ones
Just tested; Pianoteq does it (though it's subtle, you need to release it just barely, you'd better have a good analog pedal and might need to play around with the curve). Did I mention Pianoteq is amazing?
