Well you're dead right about the scenery.....I checked it out on Google Earth (very poor definition - the Yanks can't see Onerahi as a Tactical Air Force Base)..
I also did a slew over my terrain but you'll see the difference that the NZ Topo makes - I am also running the 75M Mesh.
I am very familiar with this area, having flown in and out dozens of times over the years, and also have some mates living on the seaward side of the airstrip. I consider that my corrected
NZ Topo result is about as good as you'll get given the limitations of the Simulation.
I see you state you can't afford the NZ Topo and fair enough....I can't help technically apart from commenting that it does work and is worth the bikkies if you can find them.
