Had our 35, precursor to the 40 for over 12 years now. Still works well and produces 5-6 litres an hour. Solely powered by our KISS wind generator
. Plenty to provide a backup for the two of us out cruising.
Whenever there is excess wind
we put it on and top up the tanks
. Had no problems with it at all, maintain it well, replace the main filter every 2-3 years. Highly recommend it.