I still have two early model Fox .15 Schnuerlehighbacks's flying in a couple of planes today. Both engines are early versions with a bushed crankshaft, and the early little muffler setup on them. Both engines run quite good still. Granted I am sure there are more powerful and faster .15's out there, but you would be hard pressed to get one that idled as good as these two do or have such a good throttle response too. I think my little HB .15 and a Enya .15 I have worked about this good as well.
A little Sportster plane with a Fox .15 RC. It is actually overpowered with the .15 engine on it, it can do all of the aerobatics at 1/2 throttle. But it does fly nicely and the engine works great and had a great idle too.
Then there is my Fox .15 powered Combat plane. It flies well too.. The club here stages some .15 glow and also F22 electric combat events from time to time. Usually they do it more on Tuesdays though, I miss a lot as I have to work then.