The midjay plus and the SD3 share the same styles but the SD3 has more. The Midjay also plays MP3, wavs, midi but has less buttons so your forced to a lot of menu scrolling. The SD3 is just lake the SD5 with keys. As far as the xd3 styles vs. sd3 styles. the sd3 uses a new sound engine , which I find the styles to sound much better than the xd3 styles. re-worked xd3 styles also sound better on the SD new drums.

good luck