I had 3 problems with my GT17:

1. an out of spec crankshaft that squeezed the front bearing everytime I tightened a prop. Start the engine and it would fry the bearing. Jim Willis at Agape finally diagnosed the problem and fixed it. This I consider a quality issue.
2. the RC-EXL CDI failed - not exactly a NGH problem and
3. a tendency for the engine to 'flame out' mid flight. Jim supplied me with a 4mm insulating plastic spacer and a velocity stack for the carb at no charge. This corrected this.

what I have now is a powerful little gasser [15x8 MAS 8200 rpm] that is the easiest starting engine I have. It obviously doesn't rival my DLE20s powerwise but does leave those JBA 15s in the dust. Mine is currently on a 60 size GP Revolver, and is wonderful.

I am no shill[&o], and while I'm not particularly up on any problems the 9 has had; I frankly don't see the quality issues you mention. IMO new engine designs by anybody are works in progress and losing local servicing distributors is the last thing NGH needs.