The model you ruled out is the best style edit/creation instrument of your preference models...and also is the best on board sequencer of all...Maybe you should re think your first impression...The Yamaha will work poorly with the SD-2...and the XG is far from only conforms with the way Yamaha needs it's sound engine to work with sequences (SMF)..and poorly at that..

The Korg handles sequences (SMF) much better than the Yamaha..but not nearly as well as the Roland model you mentioned..

I am just given you food for thought ..based on my own experiences..