Well, I guess the poll is because of my comment about the Rossi in a different thread. I didn't wanted to trash the rossi, but just thought that it might be better for a different use then fun fly 3D.
I have had such great results with the OS 50SX, that I will stick with it. 0 (yes none, nada, nothing) deadsticks after about 35 flights (running Wildcat YS20/20 and 12.25x3.75 APC prop). Starts at the first or second flip. I have never used a starter (not even when brand new out of the box). Awsome power on my Top Cap.
If you prefer a four stroke, then probably nothing will beat the YS. I do have a Saito 72 that I will try out on a different Fun Fly, but just because I have it already. Very reliable also.
As always, just my very own opinion
