Have it, like it.
I like the Kiwi prop and I liked dealing with them. I replaced a fixed 3-blade, so there were some definite changes. The boat's ability to slip through the water under sail in light air is much enhanced, and in general the reduction in turbulence at the stern is remarkable at any speed. Easy to install and adjust. I lost a bit in top end speed, but that hasn't been a problem for the sailing I do. Backing is much smoother with less propwalk, although it doesn't bite as hard when moving back into forward, so that's something to anticipate. All in all, since I consider my boat a sail boat and not a motorboat or a motorcruiser, I've been very glad with the switch.