I have a season on one, and would not hesitate to recommend the engine.

Like it enough to have purchased a second one, but still figuring out what they can/can't do. Recently learned, do not drag your feet coming up through the suggested prop sizes during break in. Get that 13x6 on there as soon as you can. They really quiet down and come alive with that prop.

BTW, one engine is running a Mac's pipe, the other a Bison Pitts. No problems to report with either.