I used to love thee features on the Ketron X1/SD-1 Bass Lock/Drum Lock ...it would allow you to hold the bass or drums within a particular variation and let you move to the next variation using the previous bass or drum line this was very kool and gave you so many options and combinations in real time.......also The VA7 would let you MORPH style parts also....I wish Yamaha would incoporate this into their KB's too.