I have twenty two flights on it to date.
The first three flights on it the second time out I noticed a light oil down the sides and it seemed a little louder. Took the chin cowl off and noticed both clamps loosen and tightened. Even with the loose coupler the engine pulled the 11 lb plane straight up unlimited. With the tightened coupler it was a lot quieter and pulled even better.

End story, it was worth the change. Oh and all this on one gallon of fuel.