I have been flying a Pizazz with an OS61FX since December. I have been happy with the engine choice. I can hover fairly easily with it. I moved the rudder servo to the bottom of the plane under the stab, this allowed me to get the CG to 4 1/4". I added some weight to get the CG to 4 1/2" but it became a little too twitchy at that CG. I installed some oversized foam wheels and run a 13/6 apc prop. No flutter yet, although I watch full speed dives. I think a Saito .72 will offer similar performance with a small weight savings over the OS61FX. I already had the OS61 and have been happy with it.