Friend of mine fitted 2 auto props to his 38 foot work boat about 9 or 10 years ago. He reported he had less cavitation - gained nearly 2 knots of speed for the same throttle settings and had about 40% extra power astern and was burning approx 1 1/2 gallions less of fuel for an 8 Hr trip
He reckoned maintenance was minimal about 10 min twice a year when he had the bottem power washed
Freebooter