I do not think all top 3D pilots use YS63 if you do not consider CPLR or Somenzini top 3D pilots.

CPLR uses a YS 45 a 2 stroke in his Madness Somenzini uses a YS 45 in his Hovering Cobra. Once again if you have the YS 45 use it. If you want to buy a new engine for the plane than get a 4 stroke, but the YS 45 is enough for that airplane.