The .46 UCD is not a light plane, probably in the 6lb area, but I don't have one to weigh. The YS .63 or Saito.82 are marginal for 3D on a 6lb plane IMO.
Whatever mine weighed it was plenty light enough, it would float on its wings, hang on the prop at half throttle, and do all the 3d manuvers that i could do.
It is a fairly large "40" size plane you have to keep in mind, something like 900+ squares