I'm using an OFNA failsafe in my LX Comp and have had no problems with it. It's nice and small and easy to set up.

On the issue of the engine. During break in I had the same problem and had to lean it out a little. The manual says to run it at 3 - 3 1/2 turns during break in. This is to ensure that you get enough lubrication to the piston and sleeve as they will be fitting very tight at teh top of the cylinder. Give it some time and of course when you make a change let it run for a good 10 seconds to clear the cylinder and carb so that you're running at the new setting. I currently run mine between 2 1/2 and 3 turns depending on the weather.
Hope this helps.