Martin,
Thanks for considering upgrading your SD1 Plus with the new USB & SD Audio Card reader.

To better answer your question, although you will loose your 6GB Factory Hard drive, you will gain the following:-
* Up to 64GB storage on either/both USB stick or SD card. (Just as we advised, Jerry, you can get a 32GB SD card, load all your stuff on there, stick it into the USB & SD Audio Card reader and player and ... just as you did with your internal HD, forget about it. It will always be there with you so you don't get to your show and realized you may have forgotten your songs at home!
* Capability to now play MP3, Karaoke and Wave audio files in addition to the Midi and Karaoke files you could play before. This is the big PLUS which puts you now in total control of your performance ... thus even eliminating the need for a DJ when you take a break.
* Easy transfer of data between your keyboard and your computer ... since the dinosaur Floppy is nowhere to be found. This also means you no longer have any need for the old PC/MAC cable which you needed previously to transfer data between the SD1 Plus's HD and your computer.
* Accessing files on your USB/SD card is way faster than it was with the floppy drive to.
* You loose about 0.8lbs since the Floppy drive, hard drive and it's assembly are all removed in exchange for the faster, lighter USB & Audio Card reader!

Hope this helps.

Thanks,