ok....

There's a new feature on the SD5, it's called "riff" mode. While playing a style, your able to activate a riff that will improvise from whatever chord you use, prior to hitting the riff ... while it plays, you can improvise solo's overtop of the riff, in full piano mode... select a variation and the style goes back to where you were....
Does that explanation make sense ?

The joy stick is located on the far left and just above there are 16 buttons...these buttons have some cool features...
#1. You can assign the 16 tracks associated with a midi file and instantly take parts off or on in real time...
#2. You can assign the buttons to handle the individual parts of the drum kit being used within a style or midi file..allowing real time adding and subtracting of the drum parts...

My understanding is that the SD5 has direct outputs dedicated for using a subwoofer...

What else..... hummmmm..... I'll be back