Hobbsy, I agree with you about the 150, but yours is probably worse since mine is a newer model, and most of the thrown props on that one were on the bench running it in and getting a feel for how it runs.

The Saito 91 seems to have that narrow grey area as well. I had one toss the spinner and prop at the top of a 200 foot climb on an Extra... The engine was running just great flat out on the level, and I ran about 2/3 of the tank out before it got that "sound", and decreasing RPMs as it ran through the climb. Before I could throttle it back, the prop was off and the engine stopped. I think the prop must have went at least 75 foot higher than the plane!