I have the SX-700 and use the Sandisk Cruzer 16Gb flash drives. As shown.
You can get HUGE amounts of data on to these disks, so as you've been advised, 16Gb or 32GB is more than you'll ever need.
The only thing I would say to you is this. The USB socket on the SX700 is in a very poor place.
I would ALWAYS use a short USB extension cable to connect your flash drives. It's SO EASY to catch the USB drive when it's on the instrument, and you would be looking at a very expensive repair to the USB socket. Believe me.....I've done it !! It's just too risky. Personally I would NEVER transport the keyboard with a drive sticking out....It's asking for trouble.
By using an extension lead, you eliminate all the wear and tear on the keyboard socket.
Now you can simply change drives on the extension lead without removing it from the socket. It saves wear and tear. It's also much easier to access. mine is taped to the music rest. SO easy to get to.
ALWAYS back up the contents of your Flash Drives to your PC. If you are planning on performing. Always carry a spare copy drive.
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