FWIW, we installed a KISS this past December and used it four months in the Caribbean windward islands
. Trades blow through here at 15-20 kt most of the winter, and we had several days with sustained winds in the 25 kt range with hugher gusts. The unit supplied 90% of our needs, but I must admit that I can't quote exactly what that is - electrical system
on board is not that sophisticated. We typically run the 12v fridge (huge), lights, VHF
pump and sometimes the stereo system - and we usually hae two guests on board (we run a crewed charter
operation so our electrical
use is much higher than a typical more aware cruising couple).
The KISS does go into a freewheeling mode in high winds, at which time it gets quite noisy, but when it is working in more normal winds the sound output is minimal - especially for a high output unit.
As mentioned above, we got quite proficient at grabbing the string attached to the unit to turn it out of the wind
so we could tie down the blades in a real blow. In lesser winds there is a switch you can throw which usually will stop the blades completely.
Only problem we had with the unit had to do with a very tall guest who was gesturing on the aft deck
while standing under the unit. He reached up over his head
and there was a sickening splatting noise
. Thankfully his cuts were not too bad and he retained all his fingers.
Based on talks with other cruisers and our own experience I'd buy one again.