Starboard sprint 2017 vs 2015

What do you find to be the main difference between the 2015/16 and 2017 Sprints?

Looking at the shapes, the 2017 has a wider tail and more volume in the rear half. This should make the board more stable. The wider tail should also make buoy turns easier since there will be more room for your back foot as well as more stability.

How does the fatter rear half of the 2017 board affect speed?

The new shape also seems to have less nose rocker. If this is the case, it should help in flat water but make the nose more difficult to handle in rough water.

Does the new bottom taken from the All Star help with stability?

Also, any idea how the 2017 14x21.5 compares with the 2015/16 14x23 as well as the 2017 14x23 in terms of stability and speed?

Thanks.