Apparently the final NSTB report is out. Maybe somebody has to link?
This article from (I suppose) a local newspaper makes reference to the investigation and reports that a lawsuit against RHC has been filed by the families of the two deceased.
The article mentions that the two pilots were "experienced".
As previously discussed in this thread their experience may however least have been on the accident type and if I remember correctly mostly on fix-wing aircraft. I am keen to find out what the final report makes of this.