Squeak and Herbie,
I would ask if you need 76 keys and would prefer the more weighted feel of the SD1 over the XD9. Also, so of the styles on the SD1 are not on the XD9 and if you are playing gigs for a living, I would suspect you would rather have 76 keys over 61. One more thing is the SD1 comes with a hard drive and a vocal harmony board which could be of importance to you. You have to add these to the XD9 if you want them.
George Kaye
Kaye's Music Scene
Reseda, California