Sonically , the SD1 sound better
SD1 comes with 307 styles more than XD9
SD1 stores additional styles on it's harddrive and you access those styles directly from the hard drive.
With the XD9 - if you do not have pattern expansion chip , you can have access to approximately 30 additional styles, up to 198 if you have pattern expansion chip.
With SD1 harddrive- you have access to hundreds of styles
Mic input is on the back (XLR) where the mic input is on the front of keyboard (1/4 inch)
Again , the SD1 sonically sounds a little better than the XD9.