High aspect kites are superior for going up wind and boosting . Especially in light wind! .Race kites boost so well and are exellent for geting back up wind to pop another,but when back rolling with big air I have found the edge to be very technical compared to the zephyr.The zepher is a better freestyle option and the edge just out edges the zepher in boost hieght and hang time.
I have taken core xr lightwind 17m on a twintip for a demo and it nearly riped my shoulders out of my sockets.I have bad shoulders from riding old 2008 switchblades.It has the best bottom end for scull dragging static grunt ,but if you want to get up wind I found it to be hard work and the bar pressure is quite heavy.
If its 6-10 knots and the swell is up its a good option for a downwinder.Slow but your still in the water doing something instead of wishing you were.