I have alos been using Adverrun. Initially one of the early units with straight cut gears and recently I bought the upgrade kit and installed it. I could not be happier with this unt. The latest version is very quiet and has lots of power. It does not require routine mainenance but a check of the bearings and condition of the belt is good practse after a few hundred fligts. I think the main difference between it and the Brenner in terms of how it performs is that the adverrun has the props fixed in relation to each other whilst the Brenner is geared so that the props can rotate at different speeds. I expect this would make a fifference in how it feels to fly. I have never been lucky enough to try both.