Yesterday I switched props sizes from a 12X6 to a 12X4W J&Z. I managed to hover briefly at full throttle with no reserve power to pull out on a vertical line. It is my opinion that your Saito might have enough thrust with the right prop combination to exceed the performance of my two stroke power plant. I'm only a fledgling 3D pilot and maybe my skills don't equate to the flying ability of this airframe.
From my limited experience with this plane I have found no bad traits as of yet. I have read that many modelers are using .90 size two stroke power plants maybe this is what you need for hover mode. The engine is mounted inverted and has given me no problems in this configuration.