Sure looks like a CG problem to me. That much down elevator and the fact that it lands great point me in that direction. Do you have the instructions? Look on H9's website for how far back it needs to be. I have seen a few ARF's with incidence problems but very few. I normally do the math myself to get the CG in the ballpark. Then fly to adjust everything else... I even have an android app that will do it for you if you have the measurements.
Wally