I've heard a lot about the ROTAX 912is lately. It has an Engine Management sytem to keep things simple and a redundant fuel injection system for reliability. Maintenance shoud be simpler too w/o the dual carbs. Fuel consumption is about one GPH less and that tranlates to about 15 to 20% more range in the same airframe. Kit makers are offering it for about $3,000 more.
Bob