I trialled one ... a 6 blade E-prop on my yellow 912 powered Titanium Explorer air Mentone last year ...the reports from our TAG Aussie test pilot was impressive! .... the drone-like ( swarm-of-bees-chasing-you") sound takes some getting used to! I tested it looking for extra take-off grunt from the 912 ... flying large passengers in the summer heat! It did certainly appear to get the higher payload on high DA days ... low winds , launched quicker than the stock Bolly prop! ( I felt the way we had it pitched ... reduced the cruise speed too much) I have been intending to do proper quantitive tests to compare the Bolly prop, with the E-prop & also a Sensenich I own ... but life seems too busy to play with comparative experiments ... & i need help to motivate me to gather proper data & mess with the switching process ... I'd rather fly & travel, get new ships flown off & delivered! ....so only subjective not objective input here! ... & it's a royal PITA ... pitching & changing each of the 6 blades ...several times to find the sweet-spot pitch!