If you are serious about 3D flight, then the Y.S. 1.10 is the way to go. I have flown various UCDs with different powerplants. My first one had an O.S. .91 four stroke w/ pump. It flew the plane great. I could hover, but pull out was sluggish. I have flown a buddies with a Saito 1.00 and it has better pull out but not nearly the authority of the Y.S. 1.10. If you are going to be hovering inches off the ground, you want gobs of extra thrust at your disposal and you want the dependability that the Y.S. pressurized fuel system can give you.