SD cards are just another form of solid state non volatile memory.
They are used mostly in cameras and video recorders where their flat shape is
convenient for this application. Their speed and capacity is similar to usb
speed. and capacity.
I do not think they have any particular use in a Hauptwerk organ that usb memory
sticks cannot perform (and these are not all that useful either even usb3 is not really
fast enough to be much use for an organs cache).
csw900